I agree with the comments that a subscription model and delivery through the Apple's app store seem at odds with the 'with data longevity in mind' objective.
Requiring a subscription makes me ask what happens when you stop supporting the project? Relying on the App Store makes me wonder what happens when Apple decides to ban your developer account?
I'm not saying these are dealbreakers, but I'd like to have some sort of answer to these concerns.
Having a self-hosted way to download and pay for the app would increase my confidence level, even if I did decide to purchase through the app store. Similarly, there are 'subscription' apps that let the user keep using the latest version of the app if they cancel the subscription, they are just no longer able to get updates. You can also make a pledge to open-source the app if once you're no longer commercially supporting it.
Yes, absolutely valid concerns and I've though about those.
When cancelling the subscription, all existing notes and all data remains fully accessible (read and write). It’s a knowledge base, after all. Projects with more than 50 notes will not support adding new notes, but all other features remain fully functional.
About the idea of keeping the latest version without updates: interesting, but tricky to implement in the App Store. You'd need a feature switch for everything. OS compatibility updates would still need to go through or the app would not survive in the App Store (typically this is what would get users to upgrade for apps distributed outside of the App Store).
Even if the app were to disappear, you could still access your notes with a browser and copy the data over to another app. Not as convenient as using text files, but the ability to embed images into the notes led me to go with HTML.
Requiring a subscription makes me ask what happens when you stop supporting the project? Relying on the App Store makes me wonder what happens when Apple decides to ban your developer account?
I'm not saying these are dealbreakers, but I'd like to have some sort of answer to these concerns.
Having a self-hosted way to download and pay for the app would increase my confidence level, even if I did decide to purchase through the app store. Similarly, there are 'subscription' apps that let the user keep using the latest version of the app if they cancel the subscription, they are just no longer able to get updates. You can also make a pledge to open-source the app if once you're no longer commercially supporting it.