[mattdesl]

Apparently this is exactly what is happening with Unity[1], where the TOS previously said that you can continue using an old version, but now they are walking this back and trying to apply fees retroactively. Whether this is legal or not might be debatable, but unless users mount a legal challenge they are probably stuck paying or finding another engine.

[1] https://news.ycombinator.com/item?id=37499731

[dmvdoug]

Honestly, the first thing I thought when I heard the story was “sounds like a lawsuit.”