Genuine versions of Windows are published by Microsoft, properly licensed, and supported by Microsoft or a trusted partner. You'll need a genuine version of Windows to access the optional updates and downloads that help you get the most from your PC.
To learn how to activate Windows, see Activate Windows 7 or Windows 8.1.
Note
This article doesn't apply to Windows 10. If you're using Windows 10, see Activation in Windows 10.
Here are answers to some common questions about genuine Windows software.
Look for key features of genuine Windows software, such as the Certificate of Authenticity (COA), a proof of license label, and an edge-to-edge hologram. For more information, visit the What to look for page on the Microsoft How to Tell website. Your safest option is always to buy Windows from Microsoft, or to buy a PC with Windows preinstalled directly from Microsoft or a store you know and trust.
You can't install Windows on more PCs than the Microsoft Software License Terms allow. Usually, a copy of Windows can only be installed on one PC. To learn more about licensing Windows on more than one PC, go to the Microsoft Volume Licensing website.
Yes. You'll still be able to get critical security updates. However, many updates are exclusively for customers with genuine versions of Windows. We strongly recommend that you get genuine Microsoft software immediately to keep you safer while using your PC.
- Repairs. If your PC has been repaired, you might start to see messages on your desktop that Windows isn't genuine. If the repairs required Windows to be reinstalled, the technician may have activated Windows with a different key than you used when it was originally installed. You might not see the messages until you try to download something from the Microsoft Download Center that requires validation, and validation fails. To fix the issue, you can properly activate Windows by reentering your original product key.
For other issues, you may need to buy a genuine version of Windows. - 1 License = 1 PC. Another common cause of Windows validation failure happens when you try to install Windows on more PCs than your license allows. For instance, if you purchased a copy of Windows and installed it on more than one PC, online validation might fail because the product key has already been used on another PC. The rule for most copies of Windows is that only one copy of Windows can be installed on one PC. To learn about licensing more than one PC, go to the Microsoft Volume Licensing website.
- Counterfeit software. Validation will also fail if you’ve inadvertently acquired and installed counterfeit Windows software. The Microsoft How to Tell website can help you identify counterfeit software and file a counterfeit software report if needed. Validation failure is common for versions of Windows that were purchased from an online auction site, or if Windows was on a used PC that you purchased. Remember to ask the seller for the Certificate of Authenticity and the original Windows disc, if there was one.
You’ll need a product key when you install Windows. To learn more, go to Find a product key.