This was new to me too, so here goes...

Most club floors outside of North America that i've stayed on provide free drinks and snacks in the evening, with varying degrees of generosity.

However, in the few hotels in Canada & the US where i've stayed on the club floors, they have an honor bar. This means the snacks (and sometimes) soft drinks are free, but you "pay" for the alcoholic drinks. To do this, you fill out a slip next to the bar with your room number & what you've consumed. These slips are then collected by the lounge staff & added to your overall bill.

This is where the honor element comes into it - if you are so inclined, you might be able to have say three drinks & only mark down two.

Sometimes, in-room minibars are designated as honor bars if you look at the room rate details - not quite sure why they use this definition, though!