If you have received a redeemable in-game item code with your Klei Shop order, you can enter your key in Don’t Starve Together to redeem your special in-game item. See the links below for instructions on redeeming the gift item codes for your platform.
How to redeem digital gift item codes for PlayStation 4:
How to redeem digital gift item codes for Steam (PC/Mac/Linux):
How to redeem digital gift item codes for TGP/Tecncent: http://support.kleientertainment.com/customer/en/portal/articles/2685507