yeah, if you are selling it, then you need permission...you'd have to contact the band, the label or whoever owns the rights to the song, sometimes all of them. Like if you wanted to use a Beatles song, Michael Jackson owns most of them, so you might want to give his people a call...maybe. But if you are using it for anything else, even is if is a sales tool, as long as it isn't being sold itself, you can use any music for free.