Nope. Each merchant has their custom cookie period. That hardly matches each other. In fact I haven't seen much 28 days cookie period.
Thats the information already posted in my opening post. Thanks mate. By the way lets say its 30 days. I refer someone to for example domain registrar, he signs up during those 30 days but starts spending after those 30 days. I don't get anything from him because he did not spend during the 30 days and it does not matter that he registered during those 30 days which is kind of "my refered" client anyway. And all his life spendings is because I refered him.
You can information about coolie period in the respective notes about the firms that advertise their programs.