None of the early appearances of the "Happy Birthday to You" lyrics included credits or copyright notices. The Summy Company registered a copyright in 1935, crediting authors Preston Ware Orem and Mrs. R. R. Forman. In 1988, Warner/Chappell Music purchased the company owning the copyright for US$25 million, with the value of "Happy Birthday" estimated at US$5 million. Based on the 1935 copyright registration, Warner claimed that the United States copyright will not expire until 2030, and that unauthorized public performances of the song are illegal unless royalties are paid to Warner. In one specific instance in February 2010, the royalty for a single use was said to be US$700. By one estimate, the song is the highest-earning single song in history, with estimated earnings since its creation of US$50 million. In the European Union, the copyright for the song expired on January 1, 2017.