Another ID was used to download a game and now I want to do an in-app purchase with my ID Hi I have a problem my friend downloaded games on my iPad with his ID and now with my ID want to make an in-app purchase in that game that he downloaded.

It doesn't work and this friend doesn't remember his account. I'm really advanced on this game and DO NOT WHANT TO DELETE AND REINSTALL and potentially loose my progress.

So I'd like help thank you
This has already been answered and unfortunately you'll have to delete and reinstall, but you can backup the settings first and most likely maintain your game state:

How can I make in-app purchases with a different Apple ID than the app was purchased with?