Audible membership is £7.99/month which includes unlimited listening to the Plus Catalogue + one credit per month good for any title to download and keep.

Audible members get credit(s)* good for any title regardless of price or length. Members also get unlimited listening to the Plus Catalogue – thousands of Audible Originals, podcasts and select audiobooks. And members get exclusive deals on selected titles and will never pay more than £7.99 for additional titles to download and keep.
*Number of credits vary based on your membership plan. Credits expire after upon cancellation.

There are no commitments. You can easily cancel your membership any time. All titles taken during trial and purchased with a credit are yours to keep forever.