Technically it's perpetual fallback license, which was popularized by the Jetbrain team [0]
> A perpetual fallback license is a license that allows you to use a specific version of software without an active subscription for it. The license also includes all bugfix updates, more specifically in X.Y.Z version all Z releases are included.
After 1 year, you can continue to use the app without having to upgrade. You won't receive new features, but will continue to receive bug fixes for the features released previously.
So I can argue it's not "subscription".
Plus, renewal cost 50% less, so it's not $40-$80 a year, but only $20-$40 a year after the first year.
And lastly, the app fetch model lists from OpenAI API so there is no need to "support new models".
I believe this is a sustainable pricing model for an indie developer like me. And I believe it's fair for everyone.
[0]: https://sales.jetbrains.com/hc/en-gb/articles/207240845-What...