How do I activate Windows?

I just finished reinstalling Windows 8.1—and I made sure to disable every single unnecessary feature right out of the gate to prevent the OS from nagging me (automatic updates, and so on)—but every once in a while, this blue screen pops up: "Go to PC settings to activate windows".
Does anyone know how I can finally shake this nuisance?

So, did you grab Windows from a torrent site or something? I’m guessing you don't actually have a product key to get everything activated. Just a heads-up—we can't really talk about piracy here on this forum—but if you search "how to activate Windows 8.1" on Google or YouTube, you'll find an answer in less than a minute.

Just switch over to Linux and you won't have to deal with all those activation headaches from a junk system like Windows.

Well, he really went and buried himself deep in it, didn't he?

Larry Ortiz5 said:So, did you grab Windows from a torrent site or something? I’m guessing you don't actually have a product key to get everything activated. Just a heads-up—we can't really talk about piracy here on this forum—but if you search "how to activate Windows 8.1" on Google or YouTube, you'll find an answer in less than a minute.

What do you mean we aren't allowed to talk about certain things?

And I also wrote this in English 😬 😬