for those devs that are using a free / paid app model, how do you keep track of users when they convert from the free to the paid version of the app?
Background: I have built a game app which has a free and a pro version. Users do not need to login to use the free version. When they upgrade to the pro version, Firebase / Google Analytics loose track of what that user has been doing in the past, because there is no userID tying the two apps together. This might be an edge case, but has anybody dealt with this before? Any thoughts would be appreciated