Edited January 29, 2020
at 01:22 PM
This is one of my favorite Audible deals, and doesn't seem to come up that often.
Offer available from January 13, 2020 at 12:00AM PT to January 31, 2020 at 11:59AM PT. This offer is not available to existing Audible members or customers who have been paid Audible members in the past 30 days. Offer applies only to an Audible annual membership sold by Audible.com. For the first year of your Audible membership, you will be charged the discounted price of $99.50
To be clear, you get 12 credits all at once, and they persist at least for a year (I think you can bank more than 12 but can't remember with this deal).
Note to existing subscribers, hotdogwater indicated that he was able to cancel and then resubscribe with this offer.