5. Spinrilla Pro

itunes.apple.com

This app charges you a small fee per month for the privilege of listening to their select library. While you are subscribed, you are able to listen to their music offline without the internet. If you do not want to pay, then you will need the internet in order to listen to their music. The app is only available on Apple iTunes at the moment, but they may expand onto Windows and the Android if they become more successful.