At most PlantApp is extremely bare bones even with it’s subscription model.
Pros:
It does offer a “lifetime” (one time payment) membership as well as a monthly, water calculator, and reminders for watering/misting/fertilizing/rotating.
Cons:
Most features are locked behind a paywall including diagnosis/light meter/plant ID/toxicity info and more, while some aspects are advertised as “free” within PlantApp they actually aren’t and clicking them brings you to the subscription screen where you are offered a “free trail” however no where outside of this screen does it say “Try for free” or “free trial”, It does not offer site locations, all temperature calculations are only available in celsius (this wouldn’t be a big deal if you could switch to fahrenheit, however there is nowhere in PlantApp to switch), there is no location tracking so no truly accurate temperature estimations, aside from creating a name for a plant you can not add your own photo (so no personalized plant profiles), and there is no ability to create your own personalized profile.
All in all, while it’s a great idea in theory and one of the few plant apps which offers a one-time payment, compared to others in the same field it’s honestly barebones and locks most features that would make it even at minimum worth keeping behind a paywall.