re: Question about the season finale (spoilers?) GOT

When she and a group of people were captured by soldiers last season, there was a group of 3 men in a jail wagon that caught on fire and she went over and gave the leader a knife to cut their ropes and escape out of the burning wagon. That guy was a soldier who later protected and helped Arya and killed 3 men of her choice as a reward and payback. He gave her this coin of his city where he was going and it meant something special for whoever held it, like a fraternity kinship and protection any time in the future. She used it to the Captain, who recognized the coin's importance to those who held it.