It looks like if you log in to your account, Click "My Account" in the upper right, then click "Buy More" under the pending purchases area next to the Amazon deal, it brings up your purchase. You can then scroll to the bottom and to the left of your referral link it should show 4 icons for your referrals. "You" will be gold and anyone who used your link will also, so maybe nanami can confirm that she's been credited with enough referrals to get it free.
Also, I registered an account for Jenny and used my own link for that, so I have one referral already.
