Or maybe try a reboot. I haven't used a trial either, but here's what the purchase page says:
They don't say how to restart it. I guess that means restart the computer(?)
Little Snitch has a free, built-in demo mode that provides the same protection and functionality as the full version. The demo runs for three hours, and it can be restarted as often as you like. The Network Monitor expires after 30 days.
They don't say how to restart it. I guess that means restart the computer(?)