To restrict your referral program so only customers who have previously ordered from you can send referral in your Shopify store:
- Login to your Shopify Store.
- Click Apps in the left menu.
- Find RewardStream Referrals in the list of apps and click on it
- Find the Options section and check the box to require customers to have made at least one purchase before they can send a referral. You'll also want to review the message to show to customers if they try to refer without having made a purchase from you previously.
- Click Save on the top right of the page.
Uncheck the box to make it so anyone with a My Account on your store can send referrals.