Publishing rights

Every recorded track carries two separate copyrights. The sound recording, usually called the master, covers that specific performance and normally sits with a label. Publishing covers the underlying composition, the tune and the words, and sits with the songwriters and whoever publishes on their behalf.

Using a track means clearing both. This is why creators who bought a licence and got claimed anyway are so often baffled: they cleared the recording and left the composition open. It is also why recording your own cover does not make a song free.