To get through to the final chamber containing the Philosopher's Stone Harry and Hermione have to defeat Snape's logic challenge. When Hermione discovers the correct potion they find that there is only a small quantity remaining.
"Got it," she said. "The smallest bottle will get us through the black fire - towards the Stone."
Harry looked at the tiny bottle.
"There's only enough there for one of us," he said. "That's hardly one swallow."
(Philosopher's Stone, Chapter 16, Through the Trapdoor).
I've always assumed that there wasn't much potion left because Quirrell had already consumed part of it to gain access himself. Yet Dumbledore later went through the flames to rescue Harry from Quirrell. He did this despite it being made perfectly clear that Harry had finished the potion.
"Here I come," he said and he drained the little bottle in one gulp.
(Philosopher's Stone, Chapter 16, Through the Trapdoor).
How then did Dumbledore get through the challenge? Did the bottle refill itself every time the potion was drunk (but contained a small quantity of potion so as to only allow one person entry)? Or did Dumbledore have some kind of 'cheat code' that allowed him to bypass having to drink the potion at all?