Hi,
Thanks for the message.
When the referral link is clicked, it should create a cookie, which stores the coupon code for a certain time (default 30 days). If the visitor comes back at a later date (as long as they have not cleared their cookies) then it will automatically apply the coupon code again when they visit checkout.
With the free version, currently it is not possible to permanently link that customer to the coupon, to auto apply it again every time they make a purchase.
There is however the lifetime commission module which you may find useful, which can link customers to affiliates. Learn more here: https://couponaffiliates.com/docs/pro-lifetime-commission/ – Note: This is a PRO module. For any support with the PRO version, please contact us via email using this form: https://couponaffiliates.com/contact-form/