Steps to force activation of Windows 10 Step 1: Launch the Start Menu and search for Command Prompt. Then right-click it and select "Run as Administrator" from the context menu.

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

Here are a few more answers to some nagging questions about Windows 10 upgrades and activation in the post-Anniversary-Update era.

Did you know you can install Windows 10 to any PC or Mac without an activation key? Here is how, what happens, and how you can buy a key later without ever leaving your home.