Same windows different pc

[Lukey_AMD]

Ok, throughout watching tech video's on youtube etc, I've seen people use an already installed OS on a drive for different PC's. As in, an SSD with windows on, from a different pc, and they use it for a test on new build etc.. My question is, can I use my windows 10 SSD in another pc? Instead of buying a new copy for the new pc. Also.. How much of my pc can I swap (upgrade) before needing a fresh windows? If I changed the motherboard for example, does it require a whole new copy? (something to do with the OS ties itself to your components)

 

[Unkk]

I use an external drive with Win2Go on it.
http://www.howtogeek.com/196817/how-to-create-a-windows-to-go-usb-drive-without-the-enterprise-edition/
You can use either Windows 8 or 10 with this.