Symantec Protection Engine Live Update request service is missing after upgrading to Symantec Protection Engine 8.2.1.
The Symantec Protection Engine Update Manager service has been removed and the Symantec Protection Engine Live Update request is now served by the Symantec Protection Engine service.
Windows Server
The Symantec Protection Engine Update Manager service has been removed. It's now part the Symantec Protection Engine service. See documentation.