You need to upgrade your license manager to the latest version. The Mentor website will have the latest.
As for the 2018.06 in the license key that means the license is valid for any version with a release date prior to June 2018. When was 2018.1 released? If it was released after June 2018, you will need a new license file.
This error "License server system does not support this version of this feature." is actually referring to the version string in the INCREMENT line for the license feature being too old to support the version of the application being run. To solve that, you need to download the current license file for your site, provided your support contract is current.
However, as Rachel suggested, with application upgrades an upgrade of the license manager software is often also required.
Here are links for both sources:
"Could this be because my license has vesys version number 2018.06 but this is 2018.1?"
I missed this originally. You are correct. I verified that 2018.060 is your current license version. You would need to renew support to run 2018.100.