Pools and Tickets

You can set root pool NUKE:20 pool tickets to limit Nuke licenses on the entire farm.
You can set some pool MEM:64 host tickets to limit RAM.
And set corresponding tickets to your job blocks.
So you will limil 20 NUKE tasks on the entire farm.
And each host can run 1 task with 64 MEM tickets, 2 tasks with 32, or 132 and 216 on each host.