What is the time constraint put on the merchant to charge customers on their credit card?
Edit: Country: India, Card: Amex, Purchases: Coffee and snacks
If you legally owe them the money (because you bought something and received it), they can try to charge your card anytime. If your card doesn't exist anymore, they can contact you and ask for other form of payment.
Your debt doesn't simply go away because they neglected or delayed for whatever reason to collect it.
Many countries do have a statute of limitations, which disallows following up on old debt after a certain period of silence (but I doubt any country has a year or less); some countries don't - this depends on your country. [Edit: I don't know for India]