Quite a bit harder or even impossible to prevent software being used illegally that runs on clients than server side services no?

or even paid for. They didn't say what version of Windows. It could be XP. There's still over 5 million computers running XP according to simple web search. I haven't touched Windows not much later than XP, so not really sure of the current state of running pirated Windows. Either way, GP's point is really lacking some basic reasoning