I am using RB450. Only one port is used as the public interface. Can i be assisted with the steps on how to use winbox to limit some certain IPs to a subscription plan(e.g 8am-8pm) 
? These IPs are on the internal network(172.30.x.x) and the public interface is 86.62.x.x
The easiest way to use /ip firewall filter, where you can set time and use src-address to filter specific client.