Fantasy items are those which were never produced in the time period the piece is supposed to represent having been made.
A "licensed" product is one that the original owner of the license of the product, brand, image, character has been paid for/given permission for the usage/reproduction of said product, brand, image, character by a third party.
The license can be pulled at any time if the original owner feels damage is or may occur to their reputation or that of their product, brand, image or character.
And yes an item can be a licensed fantasy!
The only time that I am aware signage would have a license number is if it were involved in some usage requiring a state/federal licensing process and would state as such on the signage.
