Once you've collected all the things for the liquor you can go to the NPCs and get as much booze as you want. You only get three of each each time though.
Just for the record, once you've collected all the liquor items and taken them to the NPC, you can sell the flute and abandon the quest and still complete it.

I thought you only got one shot at it, so when I failed I got so pissed off that I gave up on the quest. Then I found out that you get unlimited tries at it.

Still managed to complete it in the end. If you do sell the flute you need to give Huhoan 50k for the book instead. It's worth it in the end, you get something like 450 SP.
