Free IAP content for a Facebook like
In Temple Run's IAp store they give you 250 coins for free if you like their facebook page. (Actually they just redirect you to their facebook page)
I would like to do something similiar for my app. The problem is that the user should be able to do this ONLY once. (Just like a non-consumable iap content) I cannot save it in the app configs either, because the user can delete and redownload the app and the free content would up show again.
What's the best way to do this?
Why don't you keep a record of the user's who like your page, and cross-reference it with a list of the users who use your application.
For example, get the user to connect to your App using Facebook Login. Then display the Like button on your page and subscribe to the edge.create event to capture the ID of the user once they like the page. This will be the trigger to award the points / coins etc and also the point at which you record the action in your database for future reference.