The reason why you are seeing this error message is due to the configuration of the workstation policy in the Enterprise Server. There is a workstation policy named Prevent Full Disk Encryption. If this policy is enabled it will prevent full disk encryption and the error message "The licence installed on this workstation prohibits this operation" will be shown.
To resolve this, you will need to set Prevent Full Disk Encryption to No in the workstation policy. Once you have done this see the following article for details on updating the workstation(s) with the new setting: KB229 - How do I modify workstation policy?
Keywords: licence, license