Is there a way to limit WIFI usage time (eg. maximum of 1 hr) for Coffee shops?

I can give a simple tutorial first go to the address bar in your browser and type in 192.168.1.1 then enter the username and pword or the defaults if you haven't changed them then click the access restrictions tab and from there it should be pretty self explanatory you can add mutliple "rule sets" and say only allow 1 hour on Saturdays and 3 on mondays etc. hope this helps if not google your question there are much better tutorials out there on the web.