Not a lot of people know this, but restaurants usually don’t sing “Happy Birthday” because this would be a commercial use and subject to a performance royalty. However, starting today everyone is free use “Happy Birthday” without having to pay a license fee, as a California federal court ruling just entered the popular song into the public domain. Yay!
https://torrentfreak.com/happy-birthday-enters-public-domain-judge-rules-copyright-invalid-150923/