Sprint music store songs

[psvillars]

Hey I have a question sorry if it's been posted but I searched and found nothing but when you download the songs from sprint music store where does it store the license? The reason I'm asking is because I recently had to hard reset and I had to go and re-download the songs again because it couldn't find the license obviously because i erased it when I hard-resetted. I'd like to try some custom roms especially any that help with the battery life but i don't want to lose my music and definitely don't want to have to re-purchase some of my older ones. thanks for the help.