I've been waiting all this time for the pro version to release and you made it a subscription?
Don't get me wrong, $30 for an annual sub is great, there's nothing wrong with the pricing. I get that there's a problem with relative devaluing when comparing single purchase pricing to sub pricing - I understand exactly why you made the choice.
The only problem with the format is that people generally won't feel obliged to support the program so you won't build a strong community. You may end up making less money in the long run - especially if someone else builds a program with the same features and offers it as a one time purchase.
I'm going to sub for now, but once I find a program that offers the same solution that I don't have to sub to, I'll definitely be out. Customers have to gauge their earnings just as carefully as any business owner or dev.