One app that's really doing this right is Agenda, which is truly a subscription (not a rental). You pay for a year's worth of new premium features, and then when the year is up those features are yours to keep even if you stop paying.
Not sure if any other developers are using this model, but I think it strikes a balance with ongoing income and fairness to the user.
Jetbrains suite of products that I subscribe to also offer the same model. Plus, with every passing year until the third year, they reduce the price of the subscription. Much better than the sub model of other companies
With Ulysses, I initially liked the product a lot. And then I realized that these guys are really slow at rolling out features. It is as if, they are not accountable to anybody.
For e.g., a percentage of users have been asking for table support since 2014 (2013?) and their answer since then has been that we are working on it...we want to release the most perfect version ever..blah blah. Other products like Typora meanwhile are launching with these features. Meanwhile Ulysses seems to be working on their own schedule, on features they are interested in - at least this is the impression I have of Ulysses after being with them since 2015.
For e.g., their improved dashboard was not really a must-have but rather a nice-to-have. To their credit though, IMO, they are by far the best looking app in this space. Their iOS apps are mostly full fledged versions of the desktop app. This is a good app for non-scientific writers - no doubt about that. Tech and scientific writers are better served by other apps such as Emacs.
On that note, shout out to Emacs (I am using the Doom configuration). There is a learning curve but boy what a tool! This is an OS for text, not a text editor. Every other editor seems paltry by comparison. You want tables? Here you go! Oh...you want to sort your tables? Sure...go for it. You want to execute your program that is embedded with your text. Easy! It has features that I did not even know I needed until I started using it.
I wish I had invested 5 years into Emacs rather than into Ulysses. It is open source and free. Holds data in text format and not in a proprietary package that Ulysses uses.
The most painful thing right now is transferring all my content over the last 5 years (and that includes a mater's degree) over to Emacs.