Getting rid of keys?

[Fetito Fazzito]

Hello! How do I know if I do not need any longer a certain key so that I can make space in the inventory?

[Gian]

Once you use it for your last door you need it for, it will ask you "You have no use of this key anymore, through away?" You're given the option to keep it, or rid of it.

My opinion is throw it away.

[Fetito Fazzito]

Ah, thanks you!

[DarkSamus]

Always dispose of keys when the game asks.
The game only asks when the last door needed for said key has beeen unlocked and throwing it frees a space in your inventory.

[DerMilchmannAUT]

When you have unlocked the last door using a particular key (sword, armor, helmet), the game will say it has become redundant and if you want to get rid of it. Until then you can put it in your storage box, if you really need the inventory space. Old keys on the other hand will be used up when opening doors anyway.