150837 I need a paypal IPN Script

I need a paypal IPN script. I'm selling a membership access to use my software online and I'll be using Paypal IPN to verify transactions. So I need to deliver to buyers a unique code through my own code generator, so they can access my service online once they subscribed on paypal, I'll program via paypal free trials and if payment received ok customers will still have access to my service if payment failed service will be suspended, I need to send emails and I need to receive them too, but all activations, suspensions and cancellations need to be done automatically. I know it can be done, I need someone to do it, thanks