Exceptions will exist, but the general rule is such.
No, it is subscription. Much like a magazine subscription, where you are purchasing the magazine each month, you are purchasing credits each month that you can use to buy audiobooks that you then own (yes yes, do you really “””own”””” things in the digital world of licenses, blah blah). So losing access to the app, and therefore the audiobooks you purchased, is not how it is supposed to work.
But THIS is how it works. This reality doesn't fit your paradigm. But the reality prevails.
In other words, when you stop paying them.. it stops. You can no longer consume the goods, past-present-future. You call it subscription. I call it a service. Because in my mind a subscription to a Newspaper is "News-as-a-Service. I stop paying Amazon, I lose the AWS. I stop paying the Economist, I lose access to all (present-past-future) issues.
Downvote all you want. Call it what you want. Still.. someone give me an example where the subscription ENDED, and they still have access to the Benefits. If not.. you're welcome. NaaS. Unless you get the paper-copy. Then you ACTUALLY bought the "News" and ONLY because YOU control the physical medium (the paper its printed on).
Literally Audible. The person that couldn't access the app is not the norm and likely had some sort of problem. You can access the app after you cancel and can continue to download and listen to books you've already bought. That is why it is a subscription, not a service.