Yes, along these lines. The save game is just a sort of box you can keep variables in. The great thing about it, is it can remember everything even if you stop playing the game, and then start again later.
You probably wouldn’t call the variable ‘step’, though, because you’ll never remember what its for 
You might call it something like ‘Apartment door status’, and you could make it an int, but it’s easier to make it a enum type. That way, it can have values like ‘NPC’, ‘Shopping’ and ‘Toothpaste’.
So the default value of the variable ‘Apartment door status’, would be ‘NPC’. The door won’t open with this value. When you talk to the NPC, that actor updates the save game so that ‘Apartment door status’ = ‘Shopping’.
When you buy, or pick up, the toothpaste, it ( the toothpaste BP ) updates the save game variable ‘Apartment door status’ = Toothpaste, and the door will later let you back in again.
So I can make my enum type
In the save game
Inside the door BP
Inside the NPC, after the conversation
This is just a very simple mock up of what I mean, but maybe you get the idea.
I’m using a function library to talk to the save game ( much easier )
