Implying that one of the oldest still actively developed commercial text editors is not doing sustainable business practices kinda misses the mark. They’ve been at this since 1992, 34 years ago. I think they know their business.
The app store doesn’t allow for any kind of upgrade pricing, so offering a subscription allows them to operate in the app store sustainably. A shitty compromise, but i don’t blame them for making. 12 years later you can still buy without subscribing - which is what counts for me