Similar to the Unreal model. I've been thinking about this model a lot, and I love it, and I strongly believe it has a place in the future of software, but I do

Similar to the Unreal model. I've been thinking about this model a lot, and I love it, and I strongly believe it has a place in the future of software, but I don't know how it works in practice. What payment do you require? Unreal takes a percentage over your $1MM revenue, which works great for selling software, but how does it work for e.g. SaaS? Taking a cut is... unreasonable. Not to mention, it's unlikely businesses want to reveal their revenue. Do you charge a flat fee? Per seat? What about resellers?