Dialog UserState in Bot Framework is not persisting long enough

Question

I am using a property in UserState to store a token during the login process in a Dialog. I am then retrieving that token in my Bot class. It works for about 30-40 mins. Then it resets to null. I am not sure if it happens because I navigated away from the Teams chat screen or is it because of elapsed time. I’m sure the token has not expired, and even if it did I expect it to still have the stale value. I need help understanding why it is not persisting the value.