With due respect, have you considered a model of paying once, and again perhaps for major upgrades? Or perhaps a gimped free model with paid features?

Paying monthly for local software feels bizarre to me. At least with SaaS I can kinda justify it as 'not my computer.' That said, ongoing development is worth money, but I can't think of anything I use locally that I do or would pay for on a monthly subscription basis.

That said, it may just be because the idea is new to me. In any event, I wish you luck.