Put em in restaurants all the time doing just that. They create an account on an external php-mysql page then login. They get 2 hour sessions, 4 hours max per day.
MT is a good solution, but you need something external to create the accounts and do accounting.
I think I have about 25-30 restaurants using them for hotspots. Give them an export of users that have connected to their hotspot on a monthly basis via email in a csv file.