I see what you are trying to do.. This should be doable with some custom tweaking. Basically, when you drop the cookie you also need to store the URL of the landing page with it. This way when the customer goes to make a purchase you can look up and verify if the URL stored in the cookie matches the one the product is being purchased from. If it does then give commission else don’t. This is just a basic skeleton… ofcourse, you will have to make the code robust so if the affiliate sends traffic to multiple pages you store all the URLs of those pages so he can get the commission if people buy from these pages and stuff like that.