Lol! PRICELESS!

And, you know something? It would serve him right if, the moment he finished paying the bill, he was automatically teleported back to Isabelle and Elizabeth's apartment (shrinkage and all)!

Sort of a "rubber-band" spell, you might say.

Author's Response:

You might be interested to know I almost went with this ending.

Alternate ending

 “I’m kidding. It’s back to the restaurant with you.” Elizabeth chanted a spell and Allen disappeared from sight.

Allen then appeared back in the restaurant on the same seat he was originally sitting on. Unfortunately he was still no bigger than a pop can. Even worse, an uncaring waitress was hovering over him with a bill in her hands.

“I don’t care how tiny you are, someone must pay this bill.”