If you just purchased a new device that includes Office 365, we recommend redeeming (installing) Office before upgrading to Windows 10. To redeem your copy of Office, please see Install Office on your PC or Mac.
When upgrading to Windows 10, choose Keep my apps. If you choose Erase all files except personal files, the option to install Office 365 is erased.
If you chose Erase all files except personal files, contact Microsoft Support to get the information you need to install Office.
Home Use Program (HUP)
If you received Office as part of the Home Use Program (HUP), you might need to reinstall Office. You can reinstall Office at any time by going to your Order History.
If you purchased a Backup DVD or Backup USB Flash Drive, you can also use the DVD or Backup USB Flash Drive to re-install the software.
Note: You can only re-download or buy additional products if the Software Assurance agreement is still valid and you are an active employee of the company.
Volume Licensing Academic Program (VLAP)
If you received Office as part of the Volume Licensing Academic Program (VLAP), sign into the store where you ordered your Microsoft Office Professional Plus and go to your Accounts > Orders to find your product key.