i have a network as below:

The network will be splitted into 4 segments; LAN-1, LAN-2, LAN-3 and Servers. Each routers will function as hotspot gateway to control each users internet usuage. all routers will use M-RT User Manager for hotspot AAA. Each users will need to access to Servers.
Policy: Each user can used only 50MB per day at 256kbps to internet. The traffic count won include traffic in/out Servers, LAN1, LAN2 and LAN3.
- How can we exclude those traffics?
- To archieve the same idea, can you propose other diagram?
Thanks for sharing your idea!!