How to Disconnect a static ip user after the session is over ??

I have a static ip network, whereby i assign the ip address to each client machine.
all i want to do is disconnect the user after one month of usage.

like pppoe and Hotspot is it possible to disconnect the users after the session time is over??
i tried /firewall address list and gave a timeout. The timeout feature works perfectly fine and the user gets disconnected after the time is over. But, the problem is if i reboot the ROS. The timeout disappears and the session expires.

Is it a bug in ROS or there is some otherway to do it??

Please Help. ASAP

Thanks & Regards
Samar Asil