How would a model where you pay per each model/weight update feel like? More similar to traditional software, where you'd get the current version, maybe even free/rebated version upgrade to the next, but then have to do another purchase to get the latest version? Or something similar to that?

Feels like it'd be more aligned with how the business and users would produce and use it, it'd be something like: "We've done a bunch of research and output, here is the thing, you can buy it, and we'll work on the next, then you can pay again for the next if you'd like".