KeyServer 7.0 was released a few months back. There is no need to upgrade your license server for MacVector. However, if you do want to upgrade then you must download the latest installer direct from Sassafras. This version (126.96.36.199) contains important bug fixes and is a later version than the KeyServer installer on the MacVector 12.5 CD.
You will also need to contact MacVector Support to request a new network license.