The seasonal Audible deal has returned. Starting now and running through July 31 (including Amazon Prime Day), you can sign up for three months of Audible Premium Plus for just $0.99 per month. Premium Plus is Audible's highest tier plan and normally costs $14.95/mo. As a additional subscription perk, you get a free audiobook of your choice for each of those three months and you get to keep them indefinitely.
Both new and currently expired Audible customers are eligible
Anyone who doesn't currently have an active Audible membership should be eligible. That includes new subscribers as well as existing members whose subscriptions have since expired. There's always a small your-mileage-may-vary disclaimer with these types of promotions, but fortunately it's easy to check if you qualify: log into your account, and if you see the $0.99/mo banner right on Amazon's Audible page then you're eligible for this promotion.