You can renew or extend your Office 365 for home subscription by purchasing a renewal at anytime.
Go to Office.com/renew.
Choose the Office 365 plan you're currently using.
Choose whether you want to renew for the year or monthly.
Sign in to the Microsoft Account you use for Office.
Choose Renew subscription.
Note: Automatic renewal is turned on by default when you renew online but you can turn it off at anytime.
To renew your Office 365 for home subscription online, go to Office.com/renew.
Choose the plan you're currently using and then choose whether you want to renew for the year or renew monthly.
Renewing your subscription online turns on automatic renewal so you’ll experience uninterrupted service.
You'll need to sign in to the Microsoft Account you use for Office.
To complete the transaction, choose Renew subscription.
To see the new expiration date for your subscription, go to Office.com/myaccount under the Manage account section.