A referral code can be entered by tapping:
1. Profile, (top left)
2. Enter invite code,
3. Enter the referral code!
Though, if your friend sent you a link to join Drop, the referral code will apply automatically so you can skip the steps above! When the "Enter Invite Code," label doesn't appear when you tapped onto your Profile, it means that a referral code has already applied to your account!
If you are looking to refer a friend, be sure to give them your referral code so they can enter this when signing up (followed by linking a card and confirming their email ) so that both of you can earn the referral bonus!