How to stop requiring apple I'd whenever opening an app on iPhone?

I have installed apps from my friend's account and now I signed in into my account and whenever I open the apps which are installed from my friend's account it requires an apple ID so what can I do to get them back to work?!
P.s: I don't know my friend's account:/

You have to delete your Friend's Apps. You borrowed property from him. You must have your own installed. This is a security feature that only allows applications you purchased on the mobile device, and nobody elses.

Alternatively, you can ask for all his.ipa files in %UserProfile%\My Documents\My Music\iTunes\Mobile Applications.

Obviously thats illegal copying… For the same reason you can't copy music back and forth as that is copyright.