The current version of an application in the App Store is free and has very limited functionality. An In-App Purchase unlocks everything else.

I have decided to remove the In-App Purchase and just make the application cost the same price as the In-App Purchase did. But if I make the update now, then those users who have the free version but who have not yet paid for the In-App Purchase will get a free update into the full version.

I have removed all traces of my singleton class, PurchaseManager, from the application, so that at this point, when I build/run it, all of the features are unlocked. At this point, how can I make sure that the free-version users don't just ride an update into the full version?

Maybe there's a way to test whether the app is obtained through an update or through a purchase? That way, if it's through an update, I will see if it's the free version w/o the IAP and then force the user to purchase the IAP to continue playing.

Any ideas?