This error occurs when access to VyprVPN Licensed Server is not enabled for your account. Usually this means you are on a VyprVPN Professional Edition account, and need to upgrade to VyprVPN Licensed Server Edition to be able to register a VyprVPN Licensed Server.
Please check here for more information on which accounts can register a VyprVPN Licensed Server.
If you need any further assistance, please contact our 24/7 Customer Success Team, who would be glad to assist.