MP3 decoding was already free and got recently included in Fedora [fedoraproject.org]. But now, encoding is also free according to Fraunhofer Institute for Integrated Circuits IIS [fraunhofer.de]: "On April 23, 2017, Technicolor's mp3 licensing program for certain mp3 related patents and software of Technicolor and Fraunhofer IIS has been terminated." The Wikipedia MP3 article [wikipedia.org] confirms that.
So, do you still use an MP3 library or have you switched to another format or means of listening to music such as (spying built-in) streaming services?