The song was recently found to be in the public domain. See e.g. http://arstechnica.com/tech-policy/2016/02/happy-birthday-is-public-domain-former-owner-warnerc

The song was recently found to be in the public domain. See e.g. http://arstechnica.com/tech-policy/2016/02/happy-birthday-is-public-domain-former-owner-warnerchapell-to-pay-14m/ http://arstechnica.com/tech-policy/2016/02/happy-birthday-is...