The Microsoft 365 licenses are valid for 1 year. You can renew by purchasing the product again via this link.
You may have to log in again with your @edu.surfspot.nl account after renewal. After that, you can get back to work with Office.
Are you not able to reorder Microsoft 365? Microsoft 365 is only available to a few educational institutions via SURFspot. The reason for this is that many institutions deliver this software themselves. If you receive the message "Sorry this product is not available for your institution." then you cannot purchase this software via SURFspot.
For more information see: https://www.surfspot.nl/officestudent