Let me just say that I have used both apps independently for a couple of years. I have a Galaxy S III. Recently I replace it with same due to battery issues. I don't know if the replacement is new or used. I play Play Music and I also play Words With Friends. Recently I have had strange occurrences with the phone. When I play Words With Friends the last song I listened to on Play Music will start playing. The App is NOT running until I start playing WWF. I think this is probably a unique situation and I'll just wait until the phone is eligible for an upgrade next month.