I have been using my MacBook for a while and I decided to install Windows 10, via Bootcamp, just to see what it was like. Once I was done, I knew, because I never gave it a product key, that I would be limited on my features in things, like getting rid of a watermark or customizing my view. I was planning to get a product key, later, but I wanted to see if it was worth it. However, after using it for a couple of days, I noticed I could use it like any other PC, without annoying watermarks covering my view. So, I went into settings and saw that my PC is activated with a license that is linked to my account. Then, I check the properties of "This PC" in File Explorer and it showed a product key and that Windows 10 was activated.
I'm wondering why Windows 10 is activated and I have a product key, even though I never gave it a product key once in this mac's life. So, is Microsoft giving me a free product key with my account or did my Mac come with a free product key built-in?