Go to office.com/setup365 for office 365 setup webpage.
Sign In with your Microsoft Account or Create a New one
click Create one and enter your details to create a new Microsoft Account
Enter your Office365 Product key/Code
Enter the product key or code that comes with the Office in XXXXX-XXXXX-XXXXX-XXXXX-XXXXX format. Click Next
On Office 365 Product Page, click Install Office.
Click blue Install Office button again.
Click Install to Download setup & Download file and Run Office Installation .
Accept Prompts to Begin Installation.
Let Installation progress and Finish & Click Close and Open Apps.
Open any office 365 application on your Device
Click "Activate" option
Enter office365 product key
Sign in to your office account
Click on Submit and your office will get activated.
In the admin center, go to the Billing > Products & services page.
Choose the subscription for which you want to manage recurring billing.
Under Billing, next to Renews on or Expiring on, select edit.
In the Recurring billing settings pane, select Turn OFF to turn it off. If recurring billing is already turned off, select Monthly or Once to turn it on.
Select Submit change.