The Charm of Keeping is a small item resembling a lock. It can be found in some treasure chests, or as a rare drop from Maze Slimes.
When the player dies, the charm will activate and attempt to preserve a portion of the player's inventory and give it to the player once they respawn. The charm will be consumed in this process.
The level I charm is bronze and will keep the player's armor and currently selected item. The level II charm is silver and will keep the player's armor and full hotbar. The level III charm is gold and will keep a player's entire inventory.
Logging out or exiting after dieing before respawning will cause items that could have been saved to be forever lost. They will not even be on the ground for collection. Always click "respawn" before quitting the game.