You are obtaining "Zephyr for Jira Server:License is for an older version and maintenance has expired" even after you have renewed your license
Chances are that you are still using your old license.In case you have already renewed the license please visit the website "my.atlassian.com" .Please login with your Atlassian credentials/account.In case you are not sure of the credentials please check internally with the person on whose name the account was created..
After logging in click on "Zephyr for Jira " product among the ones listed with their SEN#.Clicking on it will expand the row and you can copy the new license key given in its corresponding place holder.
Paste the same license key after select Zephyr for Jira listed in installed Add ons at <Administration>-><Addons>-><Manage Add ons>.
Click Save.Now your new license would be updated to the system and you will be able to access Zephyr for Jira without any issues.