*** Please note*** This only applies to purchases made before April 23rd 2013
If you purchased Don't Starve through dontstarvegame.com during the early beta, you received one Chrome key and one Steam key for yourself, as well as one Chrome key and one Steam key for a friend. These are single keys that cannot be converted to another kind of key for a different platform. (i.e. a Chrome key cannot be converted to a Steam key).
When you purchased Don't Starve using the Humble widget (via the Don't Starve website) during the beta, you received a purchase email confirmation that contained a link to your unique page that contains 4 fields (2 Chrome, 2 Steam), each one containing a code when clicked and redeemed.