Someone committing a license violation does not magically grant you the ability to steal 30% of their revenue. If you want to punish the license violation, take them to court.
Also note that the software is MIT licensed. Tucking some random additional clauses on your website or somewhere else doesn't magically change the licensing, if you don't want to use MIT (and make them free to use it) then don't use MIT.
The 30% was not disclosed and applied unilaterally. Per the email exchange:
> "After check, we find your app in the black list, and a random higher rate will be applied. Usually when a guy is using a fake license key, or send unusual attacking request...
Not arguing here at all because I agree with you in principle, but I wanted to point out for the sake of consideration trust it appears the plug-in author was in Russia if I’m not mistaken. I have no idea how Russian law works with regard to this, but I think it’s somewhat unfair for us to jump to the conclusion that their courts are acting like ours; for all we (I?) know, IP law for software may not be enforceable in Russia. Or it could be dark pattern gated behind high court fees, unattainable representation, etc.
