Promote > Conversion Events > (Add/Edit) > Main > Trigger Event > Metering Limit Reached: Guest Users

Settings > Metering Profiles > Metering Profile Levels > Metering Profile Level > Security Group > Guests

Analyse > Customer Ladder Analysis

Yes. You can create a Conversion Event of type "Metering Limit Reached" and set it to the Guest User metering level.

That way, whenever a guest (non registered) user hits the metering level (for guests) the conversion event will be triggered and you can know how many times it happened by checking the Customer Ladder Analysis screen for that event.