I would suggest to make a minimum viable product, without PCG and such, as these things are very project dependent.
For licensing you should look at similar plugins on FAB. People won’t pay a yearly fee, but they will pay a single-time price. Something between 100 and 300 Euro / Dollar would be a good price, depending on the features and performance of your system.
The “Pro” price on FAB can be much higher of course.