Hi Han,
In terms of licensing a WA Agent for Remote Execution is a "plugin" on the top of the WA AE Agent,
so you will need a license for the WA AE Agent.
The "WA Agent for Remote Execution" plugin is limited to "6" Remote connection through SSH or Telnet.
But again note that with WA Agent for Remote Execution you are limited to "Remote Execution" (PROXY) job type only.
You do Not have all the other job types like File Watcher, File Trigger, FTP, SAP, ... (more than 60) other job types.
You can only run a "command" or "script" through "Telnet" or "SSH". See the following docops page for more information.
Define a Remote Execution Job - CA Workload Automation AE & Workload Control Center - CA Technologies Documentation
The WA Agent for Remote Execution has been mainly designed for running jobs on "HP Integrity NonStop" or "OpenVMS" where the standard WA Agent is not available.
I hope this can help.
Thanks,
Roya