diff --git a/csharp/App/Backend/Database/Db.cs b/csharp/App/Backend/Database/Db.cs
index 95afb8bc2..06bdbd2e7 100644
--- a/csharp/App/Backend/Database/Db.cs
+++ b/csharp/App/Backend/Database/Db.cs
@@ -216,5 +216,14 @@ public partial class Db : IDisposable
             .Where(installation => installation.Id == installationId)
             .Select(installation => installation.S3Key);
     }
+
+    public void DeleteS3KeysDaily()
+    {
+        foreach (var installation in Installations.ToList())
+        {
+            installation.S3Key = null;
+            Update(installation);
+        }
+    }
 }
 
diff --git a/csharp/App/Backend/Database/User.cs b/csharp/App/Backend/Database/User.cs
index 28c159508..b07bc6b62 100644
--- a/csharp/App/Backend/Database/User.cs
+++ b/csharp/App/Backend/Database/User.cs
@@ -152,7 +152,7 @@ public partial class Db
     //     
     // }
     
-    public Object CreateAndSaveInstallationS3ApiKey(Installation installation)
+    public Object? CreateAndSaveInstallationS3ApiKey(Installation installation)
     {
         //EXOSCALE API URL
         const String url = "https://api-ch-dk-2.exoscale.com/v2/";
diff --git a/csharp/App/Backend/Model/Installation.cs b/csharp/App/Backend/Model/Installation.cs
index b04885b40..b6c4b7968 100644
--- a/csharp/App/Backend/Model/Installation.cs
+++ b/csharp/App/Backend/Model/Installation.cs
@@ -14,7 +14,7 @@ public class Installation : TreeNode
     public Double Long { get; set; }
 
     public String S3Bucket { get; set; } = "";
-    public String S3Key    { get; set; }
+    public String? S3Key    { get; set; }
     
 }
 
diff --git a/csharp/App/Backend/Program.cs b/csharp/App/Backend/Program.cs
index ae662b779..7b6df34b9 100644
--- a/csharp/App/Backend/Program.cs
+++ b/csharp/App/Backend/Program.cs
@@ -1,3 +1,4 @@
+using System.Reactive.Linq;
 using InnovEnergy.App.Backend.Database;
 using Microsoft.OpenApi.Models;
 
@@ -10,11 +11,13 @@ public static class Program
         using (var db = Db.Connect())
             db.CreateFakeRelations();
 
+        Observable.Interval(TimeSpan.FromDays(1)).Subscribe((_) => deleteInstallationS3KeysDaily());
+        
         var builder = WebApplication.CreateBuilder(args);
-
+        
         builder.Services.AddControllers();  // TODO: remove magic, specify controllers explicitly
         // Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
-
+            
         builder.Services.AddHttpContextAccessor(); 
         builder.Services.AddEndpointsApiExplorer();
         builder.Services.AddCors(o => o.AddDefaultPolicy(p => p.WithOrigins("*").AllowAnyHeader().AllowAnyMethod()));
@@ -34,7 +37,7 @@ public static class Program
             app.UseSwagger();
             app.UseSwaggerUI(cfg => cfg.EnableFilter());
         }
-
+        
         app.UseCors();
         app.UseHttpsRedirection();
         app.UseAuthorization();
@@ -44,6 +47,13 @@ public static class Program
         app.Run();
     }
 
+    private static void deleteInstallationS3KeysDaily()
+    {
+        using var db = Db.Connect();
+        db.DeleteS3KeysDaily();
+
+    }
+
     private static async Task SetSessionUser(HttpContext ctx, RequestDelegate next)
     {
         var headers  = ctx.Request.Headers;
diff --git a/csharp/App/Backend/db.sqlite b/csharp/App/Backend/db.sqlite
index 92600a486..6b0d2d492 100644
Binary files a/csharp/App/Backend/db.sqlite and b/csharp/App/Backend/db.sqlite differ