Issue with not being stored sessions (API App)

One of the methods within an API allows the user to switch subscriptions. An active subscription is kept in the sessions.

Conditions: To start off subscription id = 3

I make two following calls: Set subscription with subscription id = 10 Get current subscription and return should be 10

I did a run using "Postman" and when calling current subscription result was 10.

However, when using VB.NET current subscription returned id = 3. Additionally to that, when testing set subscription method I have returned active subscription after change took place and subscription has indeed changed but as we can see was lost shortly afterwards.

via Chebli Mohamed