It is not necessary to buy the maps to unlock Old Dalan in the Sky Pirate's Den; it is enough to fully unveil every map by visiting every corner. If the player buys/finds a map, they don't need to completely clear out the grayed out areas, as long as the player has entered every area on the map at least once. In addition to unveiling all the maps, the player must visit every residence to unlock Old Dalan in the Sky Pirate's Den.