I recently answered a reader’s question about sorting out which app on his iPhone was prompting him for an account password. This can happen when you use a bypass to install—legitimately!—on your iOS device an app purchased by someone else. You can use that app, but iOS may prompt you to enter the Apple ID password for the account that bought it.
Reader jslove proffered a great solution in the comments that I need to bump out into a full article, because it’s an actual answer. What jslove noted is that in iTunes in OS X, you can select a synced or downloaded app and view the purchaser’s information.
Read more here:: Who owns which apps you’ve installed in iOS? A better answer