If you have MtoA 3.0.0 or later, you can use the MtoA licensing tools.
Get the name or IP address of the license server computer.
The license server computer is the computer where the RLM license server is running.On Mac OS remote machines will have .local added to the end so the server name may be LICSERVER.local in the example above
In Maya, click Arnold > Licensing > Connect to License Server
In the Solid Angle (RLM) text box, type "5053@" and then type the name of your license server computer.
If Maya is installed on the same computer as the license server, use localhost as the computer name.