Working out where to use your first Simple Key in Hollow Knight: Silksong is a tough choice, especially since there are multiple options at the start of the game, and you'll want to unlock what will benefit you the most. You can buy the Simple Key from Pebb in Bone Bottom for 500 Rosaries, which is quite a lot when you've just started exploring Pharloom.
Thankfully, there are three other Simple Key locations later in the game, and the same number of locked doors, so you're not going to miss out on anything by using your first key straight away. You'll simply have to find the others—with the help of this guide—to unlock any further doors you do run into.
