You should see the following text or something similar.

Please point your browser to the following page To download the file we need, which is called the 'Lame Mp3 Library'. This sounds complicated but what it really involved is downloading the right file and then linking to it in Audacity.

However it can't export a project as an mp3 file unless you install an extra bit of software called 'library'. this update was made to reflect the new features of Audacity Version 2.4.2.By default Audacity can play and edit mp3 files. Update July 2020: This article was originally published in May 2017 and has since been updated. We have this issue covered in the following article about converting voice memos to MP3 using Audacity in Windows 10. If you want to import M4A or AAC audio files to Audacity or convert other audio files to M4A or AAC using Audacity, you need to install another library for Audacity, the FFmpeg. Similarly, this feature can be enabled by installing extra library. Other than MP3, M4A is another popular audio format which is not supported by Audacity by default. The software patent on LAME encoding library has expired, so now the LAME library for MP3 export is built-in with Audacity for Windows and Mac. Built-in MP3 support in Audacity version 2.4.2 When the LAME library has been installed, go to record any sound in Audacity, you can directly save them as MP3 files.

The installer of Lame for Windows version 3.99.3 is less than 1MB, very light-weight. You can choose to download the installer package in either EXE or ZIP format. Follow on-screen tips to download the LAME MP3 add-on to your PC. Click the link to jump to the Installing LAME on Windows section. Hit the download button as displayed on previous screenshot, you’ll be taken to the LAME MP3 Encoder download page in your web browser. Audacity needs the file lame_enc.dll to create MP3s.

Lame encoder audacity