[yebyen]

Fusion 360 is not in any way open code though, right?

I'm thinking of any _open_ product that says you have to pay once your derivative product goes commercial, even if it's also open. That would be decidedly non-free in the sense of restrictive and as an example, this is something that is not compatible with standard GPL, and not included in the basic general BSD/MIT licenses.

My definition of a free license would include the right to sell (any developer hours for bounty, support, stickers, socks, CDs, anything I want for cash, including unmodified copies of your software) without restriction or liability from upstreams, no obligations, other than that I must include the source code and my distribution must also be similarly unencumbered and without additional restrictions.

There's no comparison to be made with "free for personal use, binaries only." (But thanks for advancing the discussion...)

[Bartweiss]

This is an interesting idea, but I wonder how fees would be assessed?

At one remove "source available, but pay for commercial use" seems very workable. The tricky part is handling it 3+ commercial layers out, where you're either building up a pyramid of fees or making direct payments several notches back along the chain. The first threatens to strangle commercial use past a few removes, the second might work better but opens all the "find the license holder" issues music has already.

I don't mean to dismiss the idea, rather I'm interested to think through what a low-impact way of implementing this might be.