You get the $25 payment when the person you have referred has topped up $25 in credit

You will receive your account credits after your referral completes $25 of billing (excluding promo credits). This typically occurs no later than the 15th of the month.

This means (assuming the user is using a single $5 droplet and has received $10 in credit being referred) it could be up to 8 months before the credit comes out of a pending state