diff --git a/DataCenter_Windows/WindowsDataCenter/Interfaces/Identifier.cs b/DataCenter_Windows/WindowsDataCenter/Interfaces/Identifier.cs
index 52766ff..00e22da 100644
--- a/DataCenter_Windows/WindowsDataCenter/Interfaces/Identifier.cs
+++ b/DataCenter_Windows/WindowsDataCenter/Interfaces/Identifier.cs
@@ -1,11 +1,13 @@
-namespace Interfaces
+using System;
+
+namespace Interfaces
 {
     public class Identifier
     {
         public int Id { get; set; }
         public string UniqueId { get; set; }
         public bool IsAssociatedToUser { get; set; }
-
+        public DateTime LastUsed { get; set; }
         public override bool Equals(object obj)
         {
             var identObj = obj as Identifier;
@@ -18,7 +20,7 @@
 
         public override int GetHashCode()
         {
-            return Id.GetHashCode() ^ UniqueId.GetHashCode() ^ IsAssociatedToUser.GetHashCode();
+            return Id.GetHashCode() ^ UniqueId.GetHashCode() ^ IsAssociatedToUser.GetHashCode() ^ LastUsed.GetHashCode();
         }
     }
 }
\ No newline at end of file