Affiliates plugin for membership site (wordpress)

Hi!
I have already set this question in the section "membership site" but have no answer!
Probably this section is more proper!
This is the situation!
I am trying to create a membership site and I want to integrate it with a affiliation system!
To every person that will bring an affiliate the subscription will be decreased!
Example:
Initial fee: 100 a month
1 affiliate fee 90 a month
2 affiliates fee 80 a month
...
...
9 affiliates fee 10 a month!
Are there any plugins or software or script for this?
Or maybe a need to pay a freelancer to create something like that?

Sorry for my english!
If you have any question or suggestion please let me know!

I don't understand what you are talking about when you do a rundown on affiliate fee.
affiliate fee?