www.office.com/setup | Enter Office Setup Key | office.com/setup

Go to www.office.com/setup.Sign in with your Microsoft account, or create one if you do not have one. Be certain to take into account this account so that you can install or reinstall Office later, without a product key.
Enter your Office product key, besides hyphens, if prompted. If you don't see the alternative to enter your product key, it was entered for you automatically.