Where can you use the key in pmdeot?

In the game "PMDEOT" (Pokémon Mystery Dungeon: Explorers of Time), the key can be used to unlock specific doors within dungeons that lead to special areas or treasure rooms. These locks often require the key to progress further or access valuable items. Additionally, it may be used in certain quests or events that require the player to find and use the key to advance the storyline.