You will be given the option to redeem your BWH Rewards Points on both Subscription and non-Subscription orders during the check out process. Your options will be available on the right hand side, and you can select which reward you would like to redeem. Once a reward has been redeemed, you will see the coupon code appear. You can copy the code, and then paste it in the discount code section on this same page. Please note, you can only apply one reward per order.
You may also choose to redeem your Rewards Points from inside your account. Here is a video showing you how to do so: Applying Reward Points to Your Orders
If you are trying to apply your Rewards Points to an existing Subscription, the process is slightly different. Here's a video showing you how to apply your points to your Subscription: Applying Reward Points to Your Subscription