Audacity is free software. You may use it for any personal, commercial, institutional or educational purpose, including installing it on as many different computers as you wish. However, if you can only save in Audacity's audio format. To export as .MP3, you will also need to download LAME. Once you have downloaded both programs, you will be able to export in .MP3 directly from the Audacity interface.
LAME is a high quality MPEG Audio Layer III (MP3) encoder licensed under the LGPL.
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