I’m not involved in piracy/DRM/gamedev but I really doubt they’ll track cracked installs and if they do, actually get indie devs to pay.
Because what’s stopping one person from “cracking” a game, then “installing” it 1,000,000 times? Whatever metric they use to track installs has to prevent abuse like this, or you’re giving random devs (of games that aren’t even popular) stupidly high bills.
When devs see more installs than purchases, they’ll dispute and claim Unity’s numbers are artificially inflated. Which is a big challenge for Unity’s massive legal team, because in the above scenario they really are. Even if Unity successfully defends the extra installs in court, it would be terrible publicity to say “well, if someone manages to install your game 1,000 times without buying it 1,000 times you’re still responsible”. Whatever negative publicity Unity already has for merely charging for installs pales in comparison, and this would actually get most devs to stop using Unity, because nobody will risk going into debt or unexpectedly losing a huge chunk of revenue for a game engine.
So, the only reasonable metric Unity has to track installs is whatever metric is used to track purchases, because if someone purchases the game 1,000,000 times and installs it, no issue, good for the dev. I just don’t see any other way which prevents easy abuse; even if it’s tied to the DRM, if there’s a way to crack the DRM but not remove the install counter, some troll is going to do it and fake absurd amounts of extra installs.