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From the Help file:

Does Process Guard protect processes if Process Guard (procguard.exe) isn't running?
Yes, protection is still active. The main Process Guard program (procguard.exe) is essentially just a configuration and realtime-viewing program, but it doesn't provide the protection - the driver does. In the case of Close Message handling, another process (pg_msgprot.exe) will be active, but all other protections are handled by the driver