Mikrotik question

i need ways to limit number of connections based on dhcp server using mikrotik Rb951 or Rb750

  for example 

i have an access point ubiquiti device connected the mikrotik and cpe device connected to the access point.
so i need to give the customer 3 users only without using hotspot and ppoe.

Yes you can configure a small subnet with a limited number of IP addresses on the interface and use routing
to get from there to the network. Of course the customer can put a NAT router behind it and serve as many
machines as they like.

so how can i do that configuration

i need any one can help this configuration simply
ptp scenerio.png