• Enter your Microsoft HUP product key to activate Office. For help, see. Note: If you bought a new, unused Office 365 product key card to renew an Office 365 subscription or to buy your trial, you can enter that product key if Office prompts you for it.
You can also enter the product key at. There are a few exceptions where you'll need to do something other than sign in. • If you bought Office Professional Plus, Visio Professional, or Project Professional through your employer's Microsoft HUP benefit, you'll need your product key to install Office on a PC. To locate your product key online, see.