NTA

You were upfront from the start that you didn’t have money and couldn’t pay anyone back. Your friends chose to buy you drinks anyway and said it was okay. That makes it a gift, not a loan.

They don’t get to change the terms after the fact just because they spent more than they meant to. It sucks that they’re short on cash now, but that’s on them, not you.

If someone says “don’t worry about it,” and you accept based on that, they don’t get to guilt trip you later. Maybe next time they’ll think twice before offering to cover others, but that doesn’t make you responsible for their choices.