.aax fileMultiple possible ways exist to extract activation data from Audible .aax-files
The simples way is just using this AAX checksum resolver
Alternatively audible-activator can be used as well
Using ffmpeg and the activation bytes, a file can easily be convertet to m4b
ffmpeg -activation_bytes [XXXXXXXX] -i [Audiobook].aax -c copy [Audiobook].m4b