Inviting friends and rewards

You can find your invite code in Settings > Account. When a friend enters it while signing up and finishes email verification, you both get credits.

Enter it in the "Invite code (optional)" field on the sign-up screen. It can't be added retroactively, so it has to go in at sign-up.

Rewards are paid for up to 20 invites. From the 21st onward the invite still works, but no credits are attached. You can check how many are left in Settings > Account.