The Registration Key is the license you purchase to activate the SlingPlayer software version for supported Mobile devices. It is available in our website at www.slingbox.com. If your Mobile device is the iPhone or the Android, you will need to visit their stores in order to purchase it.
If you are testing the 30 days free trial period, you will not need to use the Registration Key. You will be able to click on "Register later" and then you will be able to get the connection to your Slingbox.
The following link will guide you to our website if you decide to purchase the Registration Key.
The Slingbox Answers Forum Moderation Team