"Did you know... ......that if you're F2P, the key to Melzar's maze is non-recoverable after finishing the Dragon Slayer quest? So if you want to enter the maze again, be sure to keep your key. If you're P2P, you can buy another key to the maze, but you have to finish the Legends Quest first!" If you are free to play you can easily retrieve the key to melzar's maze again if you lose/drop it. Just speak to Oziach again and say that you lost the key, and woila! You have the key again.