Show HN: Dynamic perler patterns (fuse bead recipes)
beadi.fr
beadi.fr
You might need to do more to drive people to the free version to try before they buy. Have you considered different payment plans, like one offs?
Also when an image is uploaded it'd be good if the image aspect ratio was preserved so that it isn't distorted.
If there was an easy and consistent answer to pricing models a lot more people would still be in business! Especially for a hobby based service. I don't know how much market research you've done but even asking on forums would be a good way to get an idea. Monthly commitments are full on for people to make. How about bundles of uses? Like 10 uses for a few dollars?