Activation helps verify that your copy of Windows is genuine and hasn’t been used on more devices than the Microsoft Software License Terms allow. This article will help you troubleshoot and fix common activation errors in Windows. For help finding your product key, see Find your Windows product key.

You can use installation media (a USB flash drive or DVD) to install a new copy of Windows, perform a clean installation, or reinstall Windows. To create installation media, go to the software download website, where you'll find step-by-step instructions.

If Office activation fails, you'll see Unlicensed Product or Non-commercial use / Unlicensed Product in the title bar of your Office apps, and most features of Office are disabled. To restore all features of Office, you'll need to fix the problem that's causing activation to fail.

If you used a product key to get to Windows 11, then you’ll need that key again after the hardware change. To find out how to locate your key, see Find your Windows product key. For more info about product keys and digital licenses, see Activate Windows.

If you try to install and activate these versions of Office on a different computer (owned by you or someone else), or on the same computer after a hardware change, you might see an error message that says you've reached the maximum number of activations.

Some Office 2019, Office 2016, and Office 2013 products come with a product key. If yours did, before installing Microsoft 365 for the first time, sign in with an existing or new Microsoft account and enter your product key at office.com/setup .

Learn how to activate Windows using a product key or digital license, check your activation status, and link your Microsoft account.

A Windows product key is a 25-character code used to activate Windows. It looks like this: Locate your product key for Windows 10 or Windows 11. Depending on how you got your copy of Windows 10 or Windows 11, you'll need either a 25-character product key or a digital license to activate it.

A Windows product key is a 25-character code used to activate Windows. It looks like this: PRODUCT KEY: XXXXX-XXXXX-XXXXX-XXXXX-XXXXX. Locate your product key for Windows 10 or Windows 11.

If you're using a new Office 2019 product key, here are two ways to fix this issue: Update Office using the steps in Install Office updates and then try again. Install Office 2019 using the steps in Download and install or reinstall Office on a PC or Mac.