One alternative would be to do what eg. Working Copy does and what also Sketch has done.

How it's described in their docs:

"The features you unlock are permanently available and any other pro features added the next 12 months after purchase are also permanently available. After one year new pro features introduced will be locked until you purchase a upgrade. Even if you do not purchase a new unlock after 12 months, the app will still be updated with improvements and bug-fixes."

From https://workingcopyapp.com/manual/purchase

This is how the developer of it describes it:

"What Working Copy does was not hard to implement and requires no state except the app receipt making it harder to circumvent.

1) each pro feature has a release date

2) a pro feature is unlocked if the users latest iAP was made less than 366 days before release date

3) I have a single (non-consumable) iAP for first unlock & one per year for later unlocks

4) later unlocks are half priced but only available once the 1st unlock has been purchased"

From: https://mastodon.social/@palmin/111648232142415578

It offers the best of both worlds in terms of one time purchase and subscription revenue I think.

I discovered your app today, and I really liked it. However, the subscription price is too expensive, which makes me hesitate.

I understand. But unfortunately one time is not sustainable.

There's a reason why salary is paid monthly instead of once big sum.

macOS and iOS development is expensive. The app has to be updated at least once per year. And apple like to change how the code works. The exact same code that works on iOS 16 doesn't work the same as iOS 17. It needs adjustment.

Changing the code to adjust for iOS 17 can also break previous iOS 16, 15, etc.

And I haven't touched the Mac version 🥲

I haven't seen any one time purchase app that keep being maintained. Except of Things by Cultured Code. And that's a special case.

Same, I love this app but for me the pricing for the subscription is too expensive. I rather spend a good amount of money on one time purchase I guess.