Authors, composers and publishers have the right, but not the obligation, to register with Performing Rights Organizations (a.k.a Collection Societies, internationally) for the collection of royalties.
The primary function of PROs is the intermediation between copyright holders and entities who wish to use their music publicly (ex. a business establishment that broadcasts background music).
They can take the role of your lobbyist, your “agents”, and most importantly, your royalty collectors.
Music Think Tank (full article)