You only need to register if you'd like your AEP Case Manager to be informed of your successful completion of the Home Study Course.
Considering there is an AEP Case Manager in every South Carolina County, it's easy to see how your awesome 8 hours of course work could get sent to the wrong person -- causing you to miss your deadline for completion, and landing you in court with an underage drinking charge still on your record to boot.
So if you'd like to avoid that nightmare -- Register Immediately. Other than that, registration is no big deal.