you have to pay for the songs though, right?!
Well...evey week there are 3 songs available for free from the iTunes store...sometimes they are good...sometimes they aren't. Just depends on your taste. Otherwise, yes you have to pay for the songs to own them. What app were you using that gave you free music you were able to keep?
Not sure if you mean a free app or an app that let's you get free music. If you're wanting a free app that let's you purchase music then iTunes on the iPhone already let's you do that. If you search the Apps you will also be able to see if anything else fits your needs. If you're wanting an app that let's you get free music...not so sure about that (except ones that let you listen to radio stations, but not let you have free music permanently).