The Activation discount is for using the activation function within the Introductory version you downloaded, not for purchasing a full version from our online store.
You don't need to do anything until the trial period for Bluray/HD/DVD playback ends. When it does, it will pop up a dialog that lets you know instead of playing the disc. This popup supports entering the activation 30% coupon.
Note that a few people have reported issues where the activation popup doesn't appear--it's just a black screen and blurays won't play. If this has happened to you, contact customer service and they will assist in purchasing the product with the activation discount.
We're going to add a manual method to select Activation from the right-click menu until we can resolve why the popup isn't working for some people, but the current release doesn't have this yet.