The best part is that the games aren't removed from Steam, which indicates that the publisher( and the developer even) maybe changed their minds about DRM-free.....
Doubtful. If that was the case, then Team 17 (who is both the developer and publisher of the games) would have removed the rest of their catalog from here as well. A game isn't necessarily removed at the same time from all stores. Give it a week or two and it will probably be removed from Steam, as well.
or maybe a licence expired(which is very unlikely since the game doesn't contain anything licenced as far as i know).
It's possible that Team 17 might not own the original game's music but might have only licensed it. If that's the case and their license expired, then it explains why both games had to be removed, as the HD version also contains the music from the original game.