diff --git a/QRBee.Core/Client/Client.cs b/QRBee.Core/Client/Client.cs
index 75ca88b..a9a58fe 100644
--- a/QRBee.Core/Client/Client.cs
+++ b/QRBee.Core/Client/Client.cs
@@ -53,6 +53,142 @@ namespace QRBee.Core.Client
         partial void PrepareRequest(System.Net.Http.HttpClient client, System.Net.Http.HttpRequestMessage request, System.Text.StringBuilder urlBuilder);
         partial void ProcessResponse(System.Net.Http.HttpClient client, System.Net.Http.HttpResponseMessage response);
 
+        /// <returns>Success</returns>
+        /// <exception cref="ApiException">A server side error occurred.</exception>
+        public virtual System.Threading.Tasks.Task AnonymousAsync()
+        {
+            return AnonymousAsync(System.Threading.CancellationToken.None);
+        }
+
+        /// <param name="cancellationToken">A cancellation token that can be used by other objects or threads to receive notice of cancellation.</param>
+        /// <returns>Success</returns>
+        /// <exception cref="ApiException">A server side error occurred.</exception>
+        public virtual async System.Threading.Tasks.Task AnonymousAsync(System.Threading.CancellationToken cancellationToken)
+        {
+            var urlBuilder_ = new System.Text.StringBuilder();
+            urlBuilder_.Append(BaseUrl != null ? BaseUrl.TrimEnd('/') : "").Append("/");
+
+            var client_ = _httpClient;
+            var disposeClient_ = false;
+            try
+            {
+                using (var request_ = new System.Net.Http.HttpRequestMessage())
+                {
+                    request_.Method = new System.Net.Http.HttpMethod("GET");
+
+                    PrepareRequest(client_, request_, urlBuilder_);
+
+                    var url_ = urlBuilder_.ToString();
+                    request_.RequestUri = new System.Uri(url_, System.UriKind.RelativeOrAbsolute);
+
+                    PrepareRequest(client_, request_, url_);
+
+                    var response_ = await client_.SendAsync(request_, System.Net.Http.HttpCompletionOption.ResponseHeadersRead, cancellationToken).ConfigureAwait(false);
+                    var disposeResponse_ = true;
+                    try
+                    {
+                        var headers_ = System.Linq.Enumerable.ToDictionary(response_.Headers, h_ => h_.Key, h_ => h_.Value);
+                        if (response_.Content != null && response_.Content.Headers != null)
+                        {
+                            foreach (var item_ in response_.Content.Headers)
+                                headers_[item_.Key] = item_.Value;
+                        }
+
+                        ProcessResponse(client_, response_);
+
+                        var status_ = (int)response_.StatusCode;
+                        if (status_ == 200)
+                        {
+                            return;
+                        }
+                        else
+                        {
+                            var responseData_ = response_.Content == null ? null : await response_.Content.ReadAsStringAsync().ConfigureAwait(false);
+                            throw new ApiException("The HTTP status code of the response was not expected (" + status_ + ").", status_, responseData_, headers_, null);
+                        }
+                    }
+                    finally
+                    {
+                        if (disposeResponse_)
+                            response_.Dispose();
+                    }
+                }
+            }
+            finally
+            {
+                if (disposeClient_)
+                    client_.Dispose();
+            }
+        }
+
+        /// <returns>Success</returns>
+        /// <exception cref="ApiException">A server side error occurred.</exception>
+        public virtual System.Threading.Tasks.Task QRBeeAsync()
+        {
+            return QRBeeAsync(System.Threading.CancellationToken.None);
+        }
+
+        /// <param name="cancellationToken">A cancellation token that can be used by other objects or threads to receive notice of cancellation.</param>
+        /// <returns>Success</returns>
+        /// <exception cref="ApiException">A server side error occurred.</exception>
+        public virtual async System.Threading.Tasks.Task QRBeeAsync(System.Threading.CancellationToken cancellationToken)
+        {
+            var urlBuilder_ = new System.Text.StringBuilder();
+            urlBuilder_.Append(BaseUrl != null ? BaseUrl.TrimEnd('/') : "").Append("/api/QRBee");
+
+            var client_ = _httpClient;
+            var disposeClient_ = false;
+            try
+            {
+                using (var request_ = new System.Net.Http.HttpRequestMessage())
+                {
+                    request_.Method = new System.Net.Http.HttpMethod("GET");
+
+                    PrepareRequest(client_, request_, urlBuilder_);
+
+                    var url_ = urlBuilder_.ToString();
+                    request_.RequestUri = new System.Uri(url_, System.UriKind.RelativeOrAbsolute);
+
+                    PrepareRequest(client_, request_, url_);
+
+                    var response_ = await client_.SendAsync(request_, System.Net.Http.HttpCompletionOption.ResponseHeadersRead, cancellationToken).ConfigureAwait(false);
+                    var disposeResponse_ = true;
+                    try
+                    {
+                        var headers_ = System.Linq.Enumerable.ToDictionary(response_.Headers, h_ => h_.Key, h_ => h_.Value);
+                        if (response_.Content != null && response_.Content.Headers != null)
+                        {
+                            foreach (var item_ in response_.Content.Headers)
+                                headers_[item_.Key] = item_.Value;
+                        }
+
+                        ProcessResponse(client_, response_);
+
+                        var status_ = (int)response_.StatusCode;
+                        if (status_ == 200)
+                        {
+                            return;
+                        }
+                        else
+                        {
+                            var responseData_ = response_.Content == null ? null : await response_.Content.ReadAsStringAsync().ConfigureAwait(false);
+                            throw new ApiException("The HTTP status code of the response was not expected (" + status_ + ").", status_, responseData_, headers_, null);
+                        }
+                    }
+                    finally
+                    {
+                        if (disposeResponse_)
+                            response_.Dispose();
+                    }
+                }
+            }
+            finally
+            {
+                if (disposeClient_)
+                    client_.Dispose();
+            }
+        }
+
         /// <returns>Success</returns>
         /// <exception cref="ApiException">A server side error occurred.</exception>
         public virtual System.Threading.Tasks.Task<RegistrationResponse> RegisterAsync(RegistrationRequest body)
@@ -282,6 +418,77 @@ namespace QRBee.Core.Client
             }
         }
 
+        /// <returns>Success</returns>
+        /// <exception cref="ApiException">A server side error occurred.</exception>
+        public virtual System.Threading.Tasks.Task ConfirmPayAsync(PaymentConfirmation body)
+        {
+            return ConfirmPayAsync(body, System.Threading.CancellationToken.None);
+        }
+
+        /// <param name="cancellationToken">A cancellation token that can be used by other objects or threads to receive notice of cancellation.</param>
+        /// <returns>Success</returns>
+        /// <exception cref="ApiException">A server side error occurred.</exception>
+        public virtual async System.Threading.Tasks.Task ConfirmPayAsync(PaymentConfirmation body, System.Threading.CancellationToken cancellationToken)
+        {
+            var urlBuilder_ = new System.Text.StringBuilder();
+            urlBuilder_.Append(BaseUrl != null ? BaseUrl.TrimEnd('/') : "").Append("/api/QRBee/ConfirmPay");
+
+            var client_ = _httpClient;
+            var disposeClient_ = false;
+            try
+            {
+                using (var request_ = new System.Net.Http.HttpRequestMessage())
+                {
+                    var content_ = new System.Net.Http.StringContent(Newtonsoft.Json.JsonConvert.SerializeObject(body, _settings.Value));
+                    content_.Headers.ContentType = System.Net.Http.Headers.MediaTypeHeaderValue.Parse("application/json");
+                    request_.Content = content_;
+                    request_.Method = new System.Net.Http.HttpMethod("POST");
+
+                    PrepareRequest(client_, request_, urlBuilder_);
+
+                    var url_ = urlBuilder_.ToString();
+                    request_.RequestUri = new System.Uri(url_, System.UriKind.RelativeOrAbsolute);
+
+                    PrepareRequest(client_, request_, url_);
+
+                    var response_ = await client_.SendAsync(request_, System.Net.Http.HttpCompletionOption.ResponseHeadersRead, cancellationToken).ConfigureAwait(false);
+                    var disposeResponse_ = true;
+                    try
+                    {
+                        var headers_ = System.Linq.Enumerable.ToDictionary(response_.Headers, h_ => h_.Key, h_ => h_.Value);
+                        if (response_.Content != null && response_.Content.Headers != null)
+                        {
+                            foreach (var item_ in response_.Content.Headers)
+                                headers_[item_.Key] = item_.Value;
+                        }
+
+                        ProcessResponse(client_, response_);
+
+                        var status_ = (int)response_.StatusCode;
+                        if (status_ == 200)
+                        {
+                            return;
+                        }
+                        else
+                        {
+                            var responseData_ = response_.Content == null ? null : await response_.Content.ReadAsStringAsync().ConfigureAwait(false);
+                            throw new ApiException("The HTTP status code of the response was not expected (" + status_ + ").", status_, responseData_, headers_, null);
+                        }
+                    }
+                    finally
+                    {
+                        if (disposeResponse_)
+                            response_.Dispose();
+                    }
+                }
+            }
+            finally
+            {
+                if (disposeClient_)
+                    client_.Dispose();
+            }
+        }
+
         protected struct ObjectResponseResult<T>
         {
             public ObjectResponseResult(T responseObject, string responseText)
diff --git a/QRBee.Core/Data/PaymentConfirmation.cs b/QRBee.Core/Data/PaymentConfirmation.cs
new file mode 100644
index 0000000..3660a8c
--- /dev/null
+++ b/QRBee.Core/Data/PaymentConfirmation.cs
@@ -0,0 +1,11 @@
+namespace QRBee.Core.Data
+{
+    public class PaymentConfirmation
+    {
+        public string MerchantId { get; set; }
+
+        public string MerchantTransactionId { get; set; }
+
+        public string GatewayTransactionId { get; set; }
+    }
+}
diff --git a/QRBee.Core/Data/PaymentResponse.cs b/QRBee.Core/Data/PaymentResponse.cs
index dae046a..7ab7e23 100644
--- a/QRBee.Core/Data/PaymentResponse.cs
+++ b/QRBee.Core/Data/PaymentResponse.cs
@@ -4,6 +4,8 @@
     {
         public string ServerTransactionId { get; set; }
 
+        public string GatewayTransactionId { get; set; }
+
         public PaymentRequest PaymentRequest { get; set; }
 
         public DateTime ServerTimeStampUTC { get; set; }
@@ -18,6 +20,6 @@
         /// Convert PaymentResponse to string to be encrypted and transmitted back to merchant
         /// </summary>
         /// <returns>Converted string</returns>
-        public string AsDataForSignature() => $"{ServerTransactionId}|{PaymentRequest.AsString()}|{ServerTimeStampUTC:yyyy-MM-dd:HH.mm.ss.ffff}|{Success}|{RejectReason}";
+        public string AsDataForSignature() => $"{ServerTransactionId}|{GatewayTransactionId}|{PaymentRequest.AsString()}|{ServerTimeStampUTC:yyyy-MM-dd:HH.mm.ss.ffff}|{Success}|{RejectReason}";
     }
 }
diff --git a/QRBee/QRBee/ViewModels/MerchantPageViewModel.cs b/QRBee/QRBee/ViewModels/MerchantPageViewModel.cs
index 93729ee..5f09db9 100644
--- a/QRBee/QRBee/ViewModels/MerchantPageViewModel.cs
+++ b/QRBee/QRBee/ViewModels/MerchantPageViewModel.cs
@@ -80,6 +80,14 @@ namespace QRBee.ViewModels
 
                     if (check)
                     {
+                        var paymentConfirmation = new PaymentConfirmation
+                        {
+                            MerchantId = _settings.LoadSettings().ClientId,
+                            MerchantTransactionId = response.PaymentRequest.ClientResponse.MerchantRequest.MerchantTransactionId,
+                            GatewayTransactionId = response.GatewayTransactionId
+                        };
+
+                        await apiService.ConfirmPayAsync(paymentConfirmation);
                         await Application.Current.MainPage.DisplayAlert("Success", "The transaction completed successfully ", "Ok");
                     }
                     else
diff --git a/QRBeeApi/Controllers/QRBeeController.cs b/QRBeeApi/Controllers/QRBeeController.cs
index deb6441..fe36f0c 100644
--- a/QRBeeApi/Controllers/QRBeeController.cs
+++ b/QRBeeApi/Controllers/QRBeeController.cs
@@ -46,5 +46,12 @@ namespace QRBee.Api.Controllers
             _logger.LogInformation($"Trying to insert new transaction {value.ClientResponse.MerchantRequest.MerchantTransactionId}");
             return _service.Pay(value);
         }
+
+        [HttpPost("ConfirmPay")]
+        public Task ConfirmPay([FromBody] PaymentConfirmation value)
+        {
+            _logger.LogInformation($"Trying to confirm transaction with gatewayTransactionId: {value.GatewayTransactionId}");
+            return _service.ConfirmPay(value);
+        }
     }
 }
diff --git a/QRBeeApi/Program.cs b/QRBeeApi/Program.cs
index 982096f..52cfba9 100644
--- a/QRBeeApi/Program.cs
+++ b/QRBeeApi/Program.cs
@@ -32,6 +32,7 @@ builder.Services
     .AddSingleton<IPrivateKeyHandler, ServerPrivateKeyHandler>()
     .AddSingleton<ISecurityService, SecurityService>()
     .AddSingleton<IPaymentGateway, PaymentGateway>()
+    .AddSingleton<TransactionMonitoring>()
     ;
 
 var app = builder.Build();
diff --git a/QRBeeApi/Services/Database/IStorage.cs b/QRBeeApi/Services/Database/IStorage.cs
index 2ad371a..a5f9919 100644
--- a/QRBeeApi/Services/Database/IStorage.cs
+++ b/QRBeeApi/Services/Database/IStorage.cs
@@ -44,6 +44,8 @@
         /// <returns>Transaction information</returns>
         Task<TransactionInfo> GetTransactionInfoByTransactionId(string id);
 
+        Task<List<TransactionInfo>> GetTransactionsByStatus(TransactionInfo.TransactionStatus status);
+
         /// <summary>
         /// Update transaction after execution
         /// </summary>
@@ -70,5 +72,7 @@
         /// <param name="clientId">Identifier by which certificate information will be retrieved</param>
         /// <returns>Certificate information</returns>
         Task<CertificateInfo> GetCertificateInfoByUserId(string clientId);
+
+        
     }
 }
diff --git a/QRBeeApi/Services/Database/Storage.cs b/QRBeeApi/Services/Database/Storage.cs
index 3feae8d..1c5a16f 100644
--- a/QRBeeApi/Services/Database/Storage.cs
+++ b/QRBeeApi/Services/Database/Storage.cs
@@ -101,6 +101,20 @@ namespace QRBee.Api.Services.Database
             return transaction ?? throw new ApplicationException($"Transaction with Id: {id} not found.");
         }
 
+        public async Task<List<TransactionInfo>> GetTransactionsByStatus(TransactionInfo.TransactionStatus status)
+        {
+            var collection = _database.GetCollection<TransactionInfo>("Transactions");
+            using var cursor = await collection.FindAsync($"{{ Status: {(int)status} }}");
+
+            var result = new List<TransactionInfo>();
+
+            while (await cursor.MoveNextAsync())
+            {
+                result.AddRange(cursor.Current);
+            }
+            return result;
+        }
+
         public async Task UpdateTransaction(TransactionInfo info)
         {
             var collection = _database.GetCollection<TransactionInfo>("Transactions");
diff --git a/QRBeeApi/Services/Database/TransactionInfo.cs b/QRBeeApi/Services/Database/TransactionInfo.cs
index 99f46bb..d682478 100644
--- a/QRBeeApi/Services/Database/TransactionInfo.cs
+++ b/QRBeeApi/Services/Database/TransactionInfo.cs
@@ -29,6 +29,9 @@ namespace QRBee.Api.Services.Database
         [BsonId] public string Id { get; set; }
 
         [BsonIgnore] public string? TransactionId => Id;
+
+        public string? GatewayTransactionId { get; set; }
+        public string MerchantTransactionId => Request.ClientResponse.MerchantRequest.MerchantTransactionId;
         public DateTime ServerTimeStamp { get; set; }
 
         public PaymentRequest Request { get; set; }
@@ -38,6 +41,9 @@ namespace QRBee.Api.Services.Database
             Pending = 0,
             Rejected = 1,
             Succeeded = 2,
+            Confirmed = 3,
+            Cancelled = 4,
+            CancelFailed =5
         }
         public TransactionStatus Status { get; set; } = TransactionStatus.Pending;
 
diff --git a/QRBeeApi/Services/IPaymentGateway.cs b/QRBeeApi/Services/IPaymentGateway.cs
index 9603997..1b28092 100644
--- a/QRBeeApi/Services/IPaymentGateway.cs
+++ b/QRBeeApi/Services/IPaymentGateway.cs
@@ -8,10 +8,14 @@ namespace QRBee.Api.Services
     {
         public bool Success { get; init; }
         public string? ErrorMessage { get; init; }
+
+        public string? GatewayTransactionId { get; init; }
     }
 
     public interface IPaymentGateway
     {
         Task<GatewayResponse> Payment(TransactionInfo info, ClientCardData clientCardData);
+
+        Task<GatewayResponse> CancelPayment(TransactionInfo info);
     }
 }
diff --git a/QRBeeApi/Services/IQRBeeAPI.cs b/QRBeeApi/Services/IQRBeeAPI.cs
index ada8c4a..e8d4b84 100644
--- a/QRBeeApi/Services/IQRBeeAPI.cs
+++ b/QRBeeApi/Services/IQRBeeAPI.cs
@@ -27,5 +27,7 @@ namespace QRBee.Api.Services
         /// <param name="value">Payment request</param>
         Task<PaymentResponse> Pay(PaymentRequest value);
 
+        Task ConfirmPay(PaymentConfirmation value);
+
     }
 }
diff --git a/QRBeeApi/Services/PaymentGateway.cs b/QRBeeApi/Services/PaymentGateway.cs
index 0d48c74..e04e88e 100644
--- a/QRBeeApi/Services/PaymentGateway.cs
+++ b/QRBeeApi/Services/PaymentGateway.cs
@@ -20,13 +20,36 @@ internal class PaymentGateway : IPaymentGateway
             return Task.FromResult(new GatewayResponse
             {
                 Success = false,
-                ErrorMessage = "Amount is too low"
+                ErrorMessage = "Amount is too low",
+                GatewayTransactionId = Guid.NewGuid().ToString()
             });
         }
         _logger.LogInformation($"Transaction with id: {info.Id} succeeded");
         return Task.FromResult(new GatewayResponse
         {
-            Success = true
+            Success = true,
+            GatewayTransactionId = Guid.NewGuid().ToString()
+        });
+    }
+
+    public Task<GatewayResponse> CancelPayment(TransactionInfo info)
+    {
+        if (!string.IsNullOrWhiteSpace(info.GatewayTransactionId))
+        {
+            _logger.LogInformation($"Transaction with id: {info.Id} was cancelled");
+            return Task.FromResult(new GatewayResponse
+            {
+                Success = false,
+                ErrorMessage = "Either payment gateway isn't working or the transaction is old",
+                GatewayTransactionId = info.GatewayTransactionId
+            });
+        }
+
+        _logger.LogInformation($"Transaction with id: {info.Id} succeeded");
+        return Task.FromResult(new GatewayResponse
+        {
+            Success = true,
+            GatewayTransactionId = info.GatewayTransactionId
         });
     }
 }
\ No newline at end of file
diff --git a/QRBeeApi/Services/QRBeeAPIService.cs b/QRBeeApi/Services/QRBeeAPIService.cs
index de25b57..43f6d71 100644
--- a/QRBeeApi/Services/QRBeeAPIService.cs
+++ b/QRBeeApi/Services/QRBeeAPIService.cs
@@ -19,18 +19,20 @@ namespace QRBee.Api.Services
         private readonly IPrivateKeyHandler _privateKeyHandler;
         private readonly IPaymentGateway    _paymentGateway;
         private readonly ILogger<QRBeeAPIService> _logger;
+        private readonly TransactionMonitoring _transactionMonitoring;
         private static readonly object      _lock = new ();
 
         private const int MaxNameLength = 512;
         private const int MaxEmailLength = 512;
 
-        public QRBeeAPIService(IStorage storage, ISecurityService securityService, IPrivateKeyHandler privateKeyHandler, IPaymentGateway paymentGateway, ILogger<QRBeeAPIService> logger)
+        public QRBeeAPIService(IStorage storage, ISecurityService securityService, IPrivateKeyHandler privateKeyHandler, IPaymentGateway paymentGateway, ILogger<QRBeeAPIService> logger, TransactionMonitoring transactionMonitoring)
         {
             _storage           = storage;
             _securityService   = securityService;
             _privateKeyHandler = privateKeyHandler;
             _paymentGateway    = paymentGateway;
             _logger            = logger;
+            _transactionMonitoring = transactionMonitoring;
             Init(_privateKeyHandler);
         }
 
@@ -180,39 +182,41 @@ namespace QRBee.Api.Services
                 _logger.LogInformation($"Transaction=\"{tid}\" initialized");
 
                 //8. Send client card data to a payment gateway
-                var res = await _paymentGateway.Payment(info, clientCardData);
+                var gatewayResponse = await _paymentGateway.Payment(info, clientCardData);
 
                 //9. Record transaction with result
-                if (res.Success)
+                if (gatewayResponse.Success)
                 {
                     info.Status=TransactionInfo.TransactionStatus.Succeeded;
+                    info.GatewayTransactionId=gatewayResponse.GatewayTransactionId;
                 }
                 else
                 {
                     info.Status = TransactionInfo.TransactionStatus.Rejected;
-                    info.RejectReason = res.ErrorMessage;
+                    info.RejectReason = gatewayResponse.ErrorMessage;
                 }
                 await _storage.UpdateTransaction(info);
                 _logger.LogInformation($"Transaction=\"{tid}\" complete Status=\"{info.Status}\"");
 
                 //10. Make response for merchant
-                var response = MakePaymentResponse(value, info.TransactionId ?? "", info.Status==TransactionInfo.TransactionStatus.Succeeded, info.RejectReason);
+                var response = MakePaymentResponse(value, info.TransactionId ?? "", gatewayResponse.GatewayTransactionId ?? "", info.Status==TransactionInfo.TransactionStatus.Succeeded, info.RejectReason);
                 return response;
             }
             catch (Exception e)
             {
-                var response = MakePaymentResponse(value, "", false, e.Message);
+                var response = MakePaymentResponse(value, "", "", false, e.Message);
                 return response;
             }
             
         }
 
-        private PaymentResponse MakePaymentResponse(PaymentRequest value, string transactionId, bool result = true, string? errorMessage = null)
+        private PaymentResponse MakePaymentResponse(PaymentRequest value, string transactionId, string gatewayTransactionId, bool result = true, string? errorMessage = null)
         {
             
             var response = new PaymentResponse
             {
                 ServerTransactionId = transactionId,
+                GatewayTransactionId = gatewayTransactionId,
                 PaymentRequest      = value,
                 ServerTimeStampUTC  = DateTime.UtcNow,
                 Success             = result,
@@ -364,5 +368,21 @@ namespace QRBee.Api.Services
             };
         }
 
+        public async Task ConfirmPay(PaymentConfirmation value)
+        {
+            var id = $"{value.MerchantId}-{value.MerchantTransactionId}";
+            var trans = await _storage.GetTransactionInfoByTransactionId(id);
+            if (trans.GatewayTransactionId == value.GatewayTransactionId)
+            {
+                trans.Status = TransactionInfo.TransactionStatus.Confirmed;
+                await _storage.UpdateTransaction(trans);
+                _logger.LogInformation($"Transaction with MerchantTransactionId: {trans.MerchantTransactionId} confirmed");
+            }
+            else
+            {
+                throw new ApplicationException($"Transaction with gatewayTransactionId:{value.GatewayTransactionId} failed.");
+            }
+        }
+
     }
 }
diff --git a/QRBeeApi/Services/TransactionMonitoring.cs b/QRBeeApi/Services/TransactionMonitoring.cs
new file mode 100644
index 0000000..93e4cc0
--- /dev/null
+++ b/QRBeeApi/Services/TransactionMonitoring.cs
@@ -0,0 +1,80 @@
+using QRBee.Api.Services.Database;
+
+namespace QRBee.Api.Services
+{
+    public class TransactionMonitoring
+    {
+        private readonly IStorage _storage;
+        private readonly IPaymentGateway _paymentGateway;
+        private readonly ILogger<TransactionMonitoring> _logger;
+        private const double Minutes = 5;
+
+        private static bool _started;
+        private static object _syncObject = new();
+
+        public TransactionMonitoring(IStorage storage, IPaymentGateway paymentGateway, ILogger<TransactionMonitoring> logger)
+        {
+            _storage = storage;
+            _paymentGateway = paymentGateway;
+            _logger = logger;
+
+            if (_started) 
+                return;
+
+            lock (_syncObject)
+            {
+                if (_started) 
+                    return;
+
+                Task.Run(MonitoringLoop);
+                _started = true;
+            }
+
+        }
+        private async Task MonitoringLoop()
+        {
+            _logger.LogInformation("Starting monitoring loop");
+            while (true)
+            {
+                await CheckTransactions();
+                await Task.Delay(TimeSpan.FromMinutes(Minutes));
+            }
+        }
+
+        private async Task CheckTransactions()
+        {
+            var list = await _storage.GetTransactionsByStatus(TransactionInfo.TransactionStatus.Succeeded);
+            _logger.LogDebug($"Found {list.Count} unconfirmed transactions");
+
+            foreach (var transaction in list)
+            {
+                if (transaction.ServerTimeStamp + TimeSpan.FromMinutes(Minutes) > DateTime.UtcNow)
+                {
+                    _logger.LogDebug($"Transaction: {transaction.MerchantTransactionId} should not be cancelled yet (ServerTimeStamp: {transaction.ServerTimeStamp:O}, Now: {DateTime.UtcNow:O})");
+                    continue;
+                }
+
+                _logger.LogDebug($"Cancelling transaction: {transaction.MerchantTransactionId}...");
+                await CancelTransaction(transaction);
+            }
+        }
+
+        private async Task CancelTransaction(TransactionInfo transaction)
+        {
+            try
+            {
+                await _paymentGateway.CancelPayment(transaction);
+            }
+            catch (Exception e)
+            {
+                _logger.LogError(e, $"Transaction: {transaction.MerchantTransactionId} can't be cancelled: {e.Message}");
+                transaction.Status = TransactionInfo.TransactionStatus.CancelFailed;
+                await _storage.UpdateTransaction(transaction);
+                return;
+            }
+
+            transaction.Status = TransactionInfo.TransactionStatus.Cancelled;
+            await _storage.UpdateTransaction(transaction);
+        }
+    }
+}