You need an unity engine license per copy of the game? Do you have a source for that? I can't find any reference to that on their website, they even answer "Ye

You need an unity engine license per copy of the game? Do you have a source for that? I can't find any reference to that on their website, they even answer "Yes" in the FAQ on the "Do I own the content I create?" which what you mentions would make it essentially false. How does free game made on Unity works?