There are several possibilities. The majority of reasons can be removed by checking the following three options and updating, in case your version is not the latest.
Did you install the latest driver version? You can check your driver version in the Vector Hardware Config under Control Panel | Vector Hardware | Help | About. Here you will find the latest driver version: https://www.vector.com/latest_driver/. In the download preview the Vector Hardware Config version is listed.
Did you install the latest service pack for your software version? You can check the service pack of your software version under File | Help | Info. Here you will find the latest software service packs: https://www.vector.com/servicepacks/
Did you install the latest version of the Vector License Client? You can check the version of your Vector License Client under: About (the green [i] in the top left)
If you have successfully checked these three steps and the license is still not recognized, please send the following to firstname.lastname@example.org:
Vector License ID of the software
Serial Number of the hardware
Screenshot of the error message
Article ID: 1183
Last updated: 2020-04-29
Licensing -> Licensing FAQs and Answers -> Troubleshooting -> What to Do when My New Vector License Is Not Recognized https://kb.vector.com/entry/1183/