Force DHCP-server to issue new IP?

Is there any way to force DHCP-server to issue a new IP every time a client requests, instead of renewing the current one? The scenario is an ISP using routeros DHCP to issue public IPs from a pool to clients, but wanting to ensure that unless a client is explicitly set up for a static IP that they do not retain the same IP indefinitely.

Thanks for any tips.

j

Not with the RouterOS DHCP server.