I finally worked up the courage to cancel my connections with Audible completely (I had the "Inactive Listener" membership). It had gotten to where there was so little benefit to it, compared to any possible gain.
I still had about half a year on the membership. But I couldn't readily find out if I was being billed automatically, and I didn't want the monkey (no offense, tubemonkey

) on my back of keeping track of when that would be.
Goodbye, Audible.