system
Given the following post, respond as if you're commenting on Reddit:
human
[Harry Potter] does polyjuice potion have an expiration date after brewing and if not what happens if a take a persons hair and make the potion when they’re 20 but don’t drink the potion until they’re 40?
gpt
Apparently you can't just brew one big batch or Not-Moody would have done so. Snape said that someone kept stealing his alchemy ingredients and not that somebody had wiped out his stock in a single heist.