Hi Francis,

This type of error typically occurs when trying to activate a subscription license in the old version of the Zemax License Manager. Subscription licenses launched with OpticStudio 19.4, so they will need to be activated in the new version of the License Manager which became available with that version (shown below):

I would also recommend using the license with a version of OpticStudio that is version 19.4 or newer. That way, you will be able to make use of the additional subscription-only features. You can download a newer version of OpticStudio and the License Manager here: https://my.zemax.com/en-US/opticstudio-downloads/. To download the License Manager alone, look under Resource Files. 

Let me know if you have any other questions about this!

Best,

Allie