I need to make a key system that saves between screens but not sessions

I’m trying to make it so that when you eat from the food bowl you can go back into the other room and the door will be unlocked. Can anyone help? The link is https://flowlab.io/game/play/1268420.

Since your going across levels, I recommend using a Save behavior.

Saves are used to remember a number until you change it.
It even remembers when you come back to the game later.

here’s a discussion that I briefly explain save:
http://forum.flowlab.io/discussion/comment/30220/#Comment_30220

And here’s a picture to start with (In Player):
2019.10.20-16.49

Thank you so much for the help! Not only did the shop example in your other discussion about this topic inspire me, but you also helped me fix, or understand, the flaw in my system. Thanks again!