The only thing I can think of is when you refer other affiliates to a network....you end up getting a percentage of their earnings for life. I've never really heard of any offers offering continuing payments after the initial sale or action.
You don't see a lot of these because for most traditional traffic sources a front loaded offer is almost always going to work out better for all parties then a recurring subscription pay out.
The vast majority of affiliates are paying for traffic in some way. Front loaded commissions facilitate buying more traffic. If you have two affiliates competing on the same traffic source, the guy taking the front loaded commission can normally afford to bid the ad space up more.
Then there's the whole issue of the sales process for tools and other subscription products being a long and torturous process from the initial lead all the way to the final sales and up-sells. Your tracking system isnt much use when the traffic you're sending spends the next several weeks gathering information. Hence things end up just being sold as leads.