Nimja Hypnosis review
Nimja Hypnosis is an independent library of spoken hypnosis recordings with a public archive and a separate patron collection. Its author documents two ways to unlock the patron files and explains what happens to a saved copy after access ends.
A free archive and a timed unlock
The public catalog includes erotic and non-erotic recordings. Nimja describes the adult material as fictional, restricts it to listeners of legal age and identifies the recordings as his own work. The support page says a single donation opens the patron files for a little over a month. Recurring Patreon support can keep access active.
Keep a saved MP3
Dipsea documents downloads for listening inside the app. Nimja’s support page says you can keep the patron MP3s you download during your unlock. You need active access to download them again.

Anabel’s take
I'd start with the public archive and find out which recording lengths suit me. If several patron files caught my eye, the one-time unlock would give me a reason to choose what to save while the window is open.