All you have to do is exit the audible and go into Amazon. Once you have logged into Amazon, select books and then audible books. You are going to find the same selection of books that you will find in the app. But here, you can make a purchase. Once you are in that section, you can search and click any book that you want to buy, and then you will be given the option of making that purchase.
The book editing service team Just select any book, and then you will be given the option of paying with credits if you have a membership. Or as a full payment that will go into your Amazon account. After you have made the purchase, you can go back into the audible app, and you can see that the audible book has been automatically added to your library. And there, you can download it to your device.