Some of our audiobooks are not available for purchase with membership credits due to restrictions set by the publisher of the specific audiobook. If this is the case, you will see this listed on the book details page, below the purchase price:
This means that you will not able to apply a credit during checkout and will be required to complete the purchase via credit card.
To help combat the licensing limitations that we may encounter in these situations, we have lowered the à la carte purchase price of the audiobook as much as possible.
Fortunately, the majority of the audiobooks in our catalog are available to purchase with membership credits.