Protected AAC files

[gooddogs]

Hi there, I am trying to get all my music so it will play on my phone. (Galaxy S3). I have all my songs in Google play, except I have 500 songs (2 gb) which are Itunes protected AAC (?m4p). I would like to be able to get these songs to play on my phone. I can put them in the dropbox or even store them on the sd card or convert them (I can't find a free good converter). Which of these is the best option and THEN how do I play them on the phone? Is there an app? Thank you.