This article explains how to activate Windows 10. While you can use Windows 10 without activating it, you won't be able to take full advantage of its features until you do.
How to Activate Windows 10 – Complete Guide
If your Windows installation isn’t activated, you won’t be able to use Windows Defender Security Center, which helps protect your computer from viruses and other malware. If you installed a new copy of Windows on your PC, you’ll likely need to activate it with a product key or digital license. If you recently reinstalled Windows, you can use the same product key to reactivate it, or use the same digital license if it’s linked to your Microsoft account.
To see if your Windows 10 installation is activated, go to Start > Settings > Update & Security and select the Activation tab. Look in the Activation section under Windows.
If you purchased a copy of Windows 10 from a retailer, it should have included a 25-character product key. If you didn't enter one when you first installed Windows, you can activate Windows with a product key by following these steps:
