New users who enter a valid referral code get no Oobit fees on card payments for their first $500 of card spend.
The benefit lasts 60 days from when the code is entered. It ends when you reach $500 of card spend or after 60 days, whichever comes first. Any unused part expires.
To get it, enter the code before your first completed card payment. See When do I need to enter my referral promo code?