Max Daily Session key

Hi all, I am running Freeradius 1.1.7, mysql and coovachilli. I need a access plan of a maximum 2 hours per day per mac address. We want users to click an enter button rather than using vouchers/usernames, etc, How do I tie the mac address and not a username to max daily session? Do I change the sqlcounter dailycounter key from user-name to callingstatinID Can the dailycounter query be rewritten with callingstationID rather than UserName? query = "SELECT SUM(AcctSessionTime - GREATEST((%b - UNIX_TIMESTAMP(AcctStartTime)), 0)) FROM radacct WHERE UserName='%{%k}' AND UNIX_TIMESTAMP(AcctStartTime) + AcctSessionTime > '%b'" Am I on the right track here?