Affiliate programs generally try to account for click-now buy-later behavior by setting a tracking cookie on the user's browser that lasts for a period of time

Affiliate programs generally try to account for click-now buy-later behavior by setting a tracking cookie on the user's browser that lasts for a period of time - 30 days is pretty typical. Provided the user doesn't click another affiliate link (since credit is generally only given to the last affiliate clicked), Fred should eventually get credit for those future purchases. (Edit: I looked into it and Amazon only gives credit for purchases made 24 hours after the click. Ouch! This is abysmally bad for an affiliate program.) What affiliate programs (and all performance-based advertising, really) actually undervalue is the view. Fred spent all that time talking about that product, but he gets no credit for it unless the link is clicked. That's why publishers with market power sell ad space by the view, not the click, and why the rates brand advertisers are willing to pay are much higher than the number of clicks the ads generate would justify.