Why do I see an "expired" message when I use Prism after renewing my subscription license?

If you've just renewed your Prism subscription license, and you (or your users if it's a group license) still see an expiration warning when you try to use Prism, it's likely that you're using an outdated Prism release.

Updating to the latest release should resolve the problem, and let you continue using your same activation for the duration of the new license term.

If you have Prism installed, updating is easy:
Open Prism and, in the main menu, go to Help → "Check for Updates...".  Prism will automatically check for the latest version.