If you are under the impression that if 360 or Limewire don't ask for a license, youre doing something perfectly legal, then you're wrong.

This very much depends on the laws of the country that you live in.

That license pop-up is the filesharing apps. way of telling you that you are your own boss, and cannot blame the app. for making it possible to download copyright works.

Most people choose to ignore it and use "always use this answer", but for some this actually is a good thing, because they thought that by paying some scamsite X amount of dollars, they would indeed not be breaking the law. (BTW www.limewire.com is not a scamsite, and will not claim to make unlimited free music blah blah blah possible nor legal)

For more info on this use the forum search. Search for things like copyright , license , legal , illegal , riaa , maffia , dmr (or was it drm) , etc.etc.etc. You will find lots of info on the subject.