yeah i think that free version with annoying screen is a good advertisement. (or annoying popup) maybe he can add a donate link. so you dont have to pay full upgrade cost, just donate 5 bucks and the screen will go away.

i want a donate option anyway. ive purchased a few times just to donate. if he had a donate option id send him 5 bucks here and there more often than $50 bucks at once.