This has been a problem for a few users.
Can you first attempt to run this as administrator and see if that resolves this. To do that, make sure all Office applications are closed, then right-click any of the Office icons (Word, Excel etc.) and choose 'Run as Administrator'. That should then reset the permissions on the files and that should resolve this issue.
If you're still seeing the same message, please check your account. To do this, in the top right hand corner of Word and Excel you'll see your name listed. Click on this and there should be a 'Switch Account' option. On the Account screen then click 'Sign Out' to fully sign out and close the application.
Then reopen the application. In the top right hand corner should be a 'Sign in' option now. If it's still showing your name, go through the process again to sign out completely and restart Word or Excel until it's just showing 'Sign in'.
Then click 'Sign In' and make sure you use your @Exeter.ac.uk email address and password.
That should then re-register the Office Suite for you.
If you are still having issues with your account, can you please check it is working by going to http://www.office.com and sign into that site with your University of Exeter email address and password.
Once you've logged into that portal, can you check how many versions of Microsoft Office it thinks you've already installed.
Click on your name in the top right hand corner of that site and choose 'View Account'.
You'll then see an 'Install Status' in the My Account section. You can install Office on up to 5 devices at once - including PC's, Tablets and smartphones. If it has detected that you've already activated it 5 times of different devices (for example on your previous laptop), you will need to de-activate a previous installation before you can activate any further ones.
Please remember that we only provide very limited support for Students having issues with software. As long as you have installed it correctly, making sure that you have full admin rights as you install it, and then sign in with the correct details it will licence itself properly.
If you are still having issues, here are some suggestions available online that might help
http://www.itguyswa.com.au/fix-office-365-office-2016-activation-unlicensed-product-problems/
https://support.office.com/en-gb/article/Unlicensed-Product-and-activation-errors-in-Office-0d23d3c0-c19c-4b2f-9845-5344fedc4380
https://www.beinventiv.com/single-post/2015/08/20/Fix-the-Dreaded-Unlicensed-Product-Message-step-by-step
Please read through these and see if any of these suggestions resolve the issue.
Alternatively, the Office Portal (http://www.office.com) can be used to access the online version of all the Microsoft Office applications.
My university provided version of Office 365 is showing as 'Unlicenced’