I had this same question a year and a half later and you didn't address it at all. How long does the cookie last for a referral? I'm trying to figure out if it's worth sending you referrals or not. So far I've send 70 people to you through a blog post and have 1 pending referral. The majority of people won't sign up on the first visit to your site. If one of the other 69 people come back on the same browser tomorrow are they still my referral or do the have to sign up immediately? If you don't know the answer please go and ask someone in marketing.
I opened a support ticket about this and it turns out that they have their referral cookie set to expire at the end of the session which basically mean that the vast majority of your referrals won't be counted. This seem really deceptive and dishonest to me. I've sent them over 70 referrals in the past week off of my blog. Total waste of my time. I'll start funneling that traffic someplace a more honest.