Ableton Live supports several audio formats for export, so you can use the program to export your projects (*.als) as FLAC audio. No other program can work with ALS projects, so Ableton Live is your only choice here.
Convert Ableton Live project to Audio files encoded by Flac - free lossless audio codec.
We found one software available in the database for this conversion.
Microsoft Windows software - convert als to flac on Windows
Program for writing, producing and performing music
Convert from als file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.