I was connected to the Internet in a coffeeshop earlier today, but I was only allowed 30 minutes of access. I tried deleting my cookies after my time was up (though admittedly I didn't delete my Flash cookies -- would that have solved the problem?), but the connection still recognized that I'd already used 30 minutes, so I couldn't connect again.

How did the connection recognize me still? The wireless was unprotected (no code or password), it just had a portal you had to pass through upon the initial connection.

I'm not terribly familiar with web development or computer networks, so just trying to get a better idea of what's happening (and possibly to know what to do next time I use up my minutes =)).