A simple script that wraps over other utils online to convert your own audible library to a more portable / free format.
Requires Python 3.6 and up, ffmpeg and inAudible-NG tables. See this awesome tutorial on how to get the two working. You really only need steps 1-4 to get the Activation Bytes.
Then it's just a matter of calling
python convert.py -i "The Tower of the Swallow.aax" -a xxxxxx
and have your owned aax converted into mp3s, split by chapters, automatically with '_{Chapter_number}' appended to the end.
Splitting the very long audio book files by chapters seemed like a much more sensible way of handling extended audio.