Audacity is a free digital audio editor and recording application, available for Windows, Mac, GNU/Linux and other operating systems. It supports import and export MP3, WAV, WMA, AIFF, OGG, FLAC, AAC, AC3, AMR, M4A, MP2, etc.
AUP is a file extension for a project file used by Audacity audio software. AUP file contains audio project information and settings, and corresponds with a data file of the same name that contains the audio data referenced in the project file.
Step 1: Download, install and run Audacity on your computer.
Step 2: Click “File,” then “Open” and choose the AUP file you would like to convert.
Step 3: Click “File,” then click “Export as MP3.”
Step 4: Edit the audio file information before conversion.
Step 5: Click “OK” to start the AUP to MP3 conversion process.