The key word is, "them". How do you figure out who has bought your book? There are a few methods, and none of them are great: 1. You include an access key in

The key word is, "them". How do you figure out who has bought your book? There are a few methods, and none of them are great: 1. You include an access key in the content of your audiobook. This means your listeners hear an ad for the thing they already own. It also means providing a single global access key to your book (accessible by everyone), unless you convince Audible/Amazon to give every customer a different audio file (with a unique product key). 2. You coordinate with Audible/Amazon to have them send their customers an email with special access to your DRM-free copy (read: competition). Good luck. 3. You get Audible/Amazon to send their customers' email address to you, so you can send them a link to your DRM-free copy. Same as #2, but with a privacy violation.