On the off chance that you have introduced office through Microsoft HUP, at that point you need to enter the item key.
Check the technique for entering office item key here.
Introduce Office 2016/2013 : office.com/setup
Get Microsoft HUP Product Key:
Go to microsofthup.com.
Select the Order History interface in the upper right-hand corner of the page.
Enter the work email deliver that you used to purchase Office. This will send an email to yourself that contains a connection to your request history.
In the email you get, select the connection to see your request history.
On the Order History website page, select your request number.