For a Windows system:
In case you’re connected to the Internet when you install Office, activation should be automatic. If it is not, open an Office application (like Word or Excel), and go to File > Account > Activate Product.
For a Mac system:
- Open an Office application (like Word or Excel), and select Activate Now.
- Under the Get Started wizard, select the Sign in to an existing Office 365 subscription, and then sign in with the email address associated with Office.