Just open your internet browser and try visitting this site. So you need to check if the KMS server is blocked or not. KMS license has to be verified by making a connection to my KMS servers before it can be used. You need to check your internet connection again and make sure that the Windows Update service is turned on.
Follow instructions in this post to uninstall the trial license. Because in some cases, after you activate your Office using KMS license, important features are resumed but the expiration notification still remains.
However, if it is still valid, you need to remove it. This step is optional if your trial license was expired. How to renew your Office 365 license Remove your current trial license
