For free without paying, like the other GUI frameworks.

Correct. This is a class of products that I really would rather not go commercial for. It's extremely difficult to change after the fact so from a business standpoint it puts us in a place where if the vendor decides to start cranking prices or they sell their business and the new owner does, then we are in a really difficult position.

It's not actually about paying money or not, I've signed up for many a patreon or what not to support open source projects I use. I fully believe in paying people for software. But for core things like this I do prefer MIT/APACHE.