To reward your hard work, you can claim free accounts at the following milestones:
50 referrals/ month: 25k challenge account with full add-ons
100 referrals/ month: 50k challenge account with full add-ons
200 referrals/ month: 200k challenge account with full add-ons
400 referrals/ month: 400k challenge account with full add-ons
Resets at the 1st of each month.