I feel like tags would be better because every licence has a name and can have a link. So both licence name and link can be very strictly defined in terms of format and expected content. Also you can have a list of most used licences so it's more an enum / tag thing to me.

Also I can think of a few use cases quering those tags if let's say you'd like an app or page which displays tracks using certain licence. Let's someone only listens CC music or would like to play CC licenced music in public.

For this reasons I'm less in favour of using content because content is really freefrom. So it's great for lyrics and credits but maybe not licences.