After logging into your account, you'll be able to see the stats right next to your personal referral link.
Referral "terms":
Visitors = How many of your friends visited pickupmusic.com using your personal referral link.
Leads = How many of your friends signed up for a free trial to Pickup Music using your personal referral link.
Conversions = How many of your friends converted into paying members at Pickup Music using your personal referral link. For every conversion, you'll receive 1 month of free Pickup Music membership!