You activate Microsoft 365 by signing in with a Microsoft account. If we detect your Microsoft account, we'll show it on this screen. After you sign in, your product is added to your Microsoft account, so that you can reinstall it later, or manage your new subscription, without a product key.

The Bottom Line. Microsoft 365 is the best set of productivity apps for serious office work, seamlessly blending the power, speed, and security of desktop-based apps with the convenience of online and mobile platforms.