How would an NFT help here? Nobody is disputing that you bought the music (or, more precisely, bought a license for the music, that they may revoke at their dis

How would an NFT help here? Nobody is disputing that you bought the music (or, more precisely, bought a license for the music, that they may revoke at their discretion). The NFT proves nothing that a receipt wouldn't also prove. What you want is a law that forbids the current practice of revoking ownership.