While collecting keys throughout the storyline, it is very easy to forget whether the key was already used at some point or not. Plus the keys keep piling up in the inventory (more than 10 keys in early access already), which clutters the inventory.
I suggest to introduce some sort of key-ring system (container in inventory or something like that) which holds keys and - more importantly - gives the player the information whether a key was already used to open a lock at some point. Knowing that a key in the inventory still haven't found its lock would give a nice hint in questing, imo.
