Three routes credit a referral, and they are checked in a fixed order so two affiliates can never claim the same sale.
1. Referral link
A visit to https://yoursite.com/?ref=jane records a first-party visit and sets a first-party cookie. The parameter name and the cookie window are both configurable. Because the cookie is first-party, a browser or an ad blocker stripping third-party scripts does not quietly stop crediting the referral — there is no third-party script to strip.
2. Coupon code
A coupon tied to an affiliate credits them on any order that uses it — no link, no cookie, no click. This is what makes an influencer programme work when the audience hears a code on a podcast and types your domain directly.
3. Customer binding
Once a customer has been referred, you can bind them to that affiliate permanently, so repeat orders keep paying the person who found them.
One order, one commission
If a visitor arrives on Jane’s link and then uses Mikael’s coupon, exactly one of them is paid — the order the routes are checked in decides, and it is the same order every time. Double-crediting is not a setting you can get wrong.
What is recorded
Every visit stores the referrer, the landing URL, the campaign and a truncated IP, subject to your retention setting. The commission is calculated when the order completes, not when the click happens — so an abandoned cart costs an affiliate nothing and earns them nothing.
When attribution is wrong
Open the referral and look at its visit. The landing URL and referrer are recorded on the row, which usually answers the question in one glance: a missing campaign means the link was shortened by someone who dropped the query string, and a referrer from your own domain means the visitor bounced through an internal page that reset it.