Unless something has changed, the iOS version is a one-time purchase. I bought the app many years ago (8?) and have been a happy user since.

Like you, though, I had that reaction to the subscription model for macOS and therefore decided not to "buy" it when it came out.

They got greedy and decided to milk it. That's what changed.

It's $80/yr for the iOS app.

Oof, I believe they changed ownership so I must have been grandfathered in. That's steep.