Purchased versions of licenses no longer have any purpose now that Fusion Pro is available at no charge for personal, educational, and commercial use.
Broadcom removed the ability for all Fusion versions to perform in-product updates as a part of a broader change to their software update policies. What you're seeing is a known issue and has been widely reported here in the forum.
A side effect of these changes is that the check for updates feature no longer works. You'll have to either monitor the Fusion release notes for new versions or watch here in the forum for notices of updated Fusion versions.
To update Fusion, download any available newer versions from Broadcom's software download portal and run that version's installer. The current (as of 18-August-2025) version of Fusion 1s 13.6.4.
I would hope that Broadcom would consider returning the check for available updates into the product, even if they decide that they won't return in-product updating. That would at least let us know that a new version was available.