 A full MPEG-1 decoder and encoder, with "Layer III audio", could not be implemented royalty free since there were companies that required patent fees for implementations of MPEG-1 Audio Layer III, as discussed in the MP3 article.All patents in the world connected to MP3 expired 30 December 2017, which makes this format totally free for use.On 23 April 2017, Fraunhofer IIS stopped charging for Technicolor's MP3 licensing program for certain MP3 related patents and software.