Music Files from Bear share won't play on any other computer?

I paid the $7 to use bearshare, and downloaded a bunch of music, some mp3's and some wma's. They play fine on my computer. I copied them to a flash drive and tried to play them on my computer at work, and they won't play. It says they don't have a licesnce or something like that. Is there a way to get them to play on other devices??