Lack of ending

I intended to make this thing so that if you had the key and unlocked the mousehole, it would enable an ending to be interacted with or sOMETHING but I just could not get it to work, because I don't understand how to implement the hack that seemed the most useful, and there are not a lot of really comprehensive tutorials out there.

I would ideally liked to be able to have some kind of conditional so that if the player picks up the key it enables an ending, or changes the exit to an ending, or something, but I just don't know.

I tried to use the dialogue ending hack but I couldn't get it working.

For now the door just keeps teleporting you back to the entrance. Maybe I will get it working later.

(the key is the sparkly smoke above the righthand machine)