You can rent a stall in Market Square when you dropped gold in front while no one else is renting it. You can only pay rent for 7 days maximum (1 week). After that, you will need to pay gold before your rent expires, or else your ownership of the stall will be lost.
In paying rent, someone else can also pay for your rent by dropping gold in front of the door, without losing the ownership as long as it is paid before your ownership expires.
In your case, you dropped your gold in front of the door of the stall that’s why your gold is used to pay rent.