Recommendations - Affiliate Network Software

Hi Guys,
My last post got deleted by the mods for "self promotion" so I will have to be a bit more vague here:
I am looking for any expert recommendations for affiliate tracking platform software that I can self-host - as cheap as possible as well.

*Before we start discussing the in's-and-out's of self-hosting, I should explain that I am not interested in using this software to run an affiliate network:
- we don't have a website to monitor or traffic to count,
- we are not interested in advertising feeds from 3rd party networks,
- we will not initially have more than 100s of monthly events, rising to a few 1000 and
- we don't need to attract external affiliates marketers to the network (so no trust issues).

I previously gave a fictitious business case here to explain it better but I think that's why my last post was deleted.
I have cut that out so as vaguely as possible:

Our software is loaded onto a set of mobile phones for our clients, who, using the software on these mobiles phones, deliver a service to their clients. They charge their clients for this service and we in turn charge them a commission - depending on what bits of the software they use. I can't really go into any more details apparently!
However, it is for this reason we want to add affiliate tracking software so that we can track what they do with the clients and then bill them only for what they use, not just at a flat rate.

We have full control over the software so we can ping the server each time some event happens however I would like to structure it like an affiliate program, perhaps with tiered pricing models, affiliate groups for similar clients etc. etc. to have full visibility of each client's behaviour. In this case what we want is a platform that can:
- track when the app is opened (session started),
- then track which content was accessed during this session (impression tracking for example)
- assign a price to certain actions (like a CPA action) so that
- we can bill them (semi)automatically in the end of each cycle according to exactly what they have used.

I have considered using analytics software but as far as I am aware,
- this software doesn't come with a login for the customer to check their billing (in the case of an affiliate platform this would be the affiliate's login to the platform) and
- it's not set up for billing clients?
- And perhaps incorrectly I feel that affiliate platform would be easier to setup this way?
Or am I wrong?

Does anyone have any recommendations/feedback/suggestions?

Thanks in advance and I look forward to hearing from you.