Customer has to refresh their license key on Tableau desktop/ Tableau server separately. Follow below guidance:
Refreshing the product key(s) updates the product key with the new date that reflects the new expiration dates.
If you refresh a subscription (term) product key before the expiration date occurs, the product key will not change but the expiration date will.
This can create a mismatch between the product keys listed in the Tableau Customer Portal and those listed in the Tableau Server TSM product key list.
The product key will change when the expiration date occurs or shortly thereafter.
If a subscription (term) product key is not refreshed and has expired, Tableau will stop working and you will have to activate a new product key in the Tableau Customer Portal.
As long as the expiry date is updated, there is no issue for customer to access Tableau.
Please explain the license key mechanism to customer and ask them to wait till May 17,2021 then the license key will update.