Your Windows 10 product key may be necessary to unlock all features -- but it's not easy to find. Here's where to look for the product key (even if it's lost).

Windows remains functional without activation, but you'll be locked out of personalization and other non-essential features until it's addressed.

Product key and activation with Windows 10 free upgrade: When you upgrade your PC to Windows 10 from Windows 8 or 7, your licence will be tied to the hardware upgrade, not to the Microsoft account.

Windows activation is alive and well in Windows 10. Microsoft doesn't like to talk about the inner workings of its anti-piracy software, but it's clear from testing that Windows 10 included a ...