Other than a Service using Windows, a so-called Daemon using Mac can either be started when a User is logged in or (alternatively) when the system is started:

Copy the attached plist file to the following location:

/Library/LaunchAgents 

(for run at Login)

or to

/Library/LaunchDaemons

(for run at Boot)

The agent will be activated with the follwing call:

Terminal:
launchctl load /Library/LaunchAgents/com.callassoftware.pdftoolboxserver.agent.plist

Using the following call, the agent can be deactivated:

Terminal:

launchctl unload /Library/LaunchAgents/com.callassoftware.pdftoolboxserver.agent.plist

If a Server-Job is active, this Job will start as soon as the sytem is started and files in the respective hot folders will be processed.