I'd like to monetise currently free features of my app in future releases. Since I don't want to agitate existing users I want to make sure things stay free for them.
In order to find out whether they had used my app before the new release I'd like to find a way to acquire the date when they first installed the app or downloaded it from the App Store.
I've found this discussion: Detect first launch of iOS app
But it stores the first launch in the user defaults of the app, which to my knowledge, will be wiped once the app is deleted. My app does not communicate with any online service/data base where I could store such information.
Is there a way to do what I'm looking for?
If there is another way please point me into the right direction.