> You want to charge based on the value that you deliver.

Charging per key reduces the value in my opinion, exactly for the reason I stated above. It puts blocks at the point where the product is most useful (Adding a key).

I can live with extra cost when a new developer is brought on board. There's already a few things I need to buy to bring them on, and this is a reasonable extra cost. But adding charges when I add key adds friction exactly at the point where I want the product to reduce it.