To restrict your referral program so only customers who have previously ordered from you can send referral in your WooCommercestore:
- Login to your Wordpress Dashboard.
- Click WooCommerce and click Referrals in the left menu.
- Find the Require Purchase 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 Settings at the bottom left of the page.
Uncheck the box to make it so anyone with a My Account on your store can send referrals.