Licensing System for PHP Scripts

I need a licensing system for my current (& future) PHP scripts, so i can LOCK/ UN-LOCK the PHP scripts sold to my clients. ## Deliverables The Licensing system for PHP scripts should work in this way... Step #1) A customer will download a PHP script from any one of my websites. He/she needs a "un-lock key" to install/use the script on their server/website Step #2) He/she will fill a registration form on my site [Fields needed: Name, Email address, the Website URL from where they downloaded the script, One extra field (customizable later on from admin panel)] Once they register, they will receive an email with an UNLOCK KEY which is automatically generated by the Licensing system. (the customer can enter this un-lock key to install/use the PHP script. Without the un-lock key the script should not work) Note: By Default, the script should work only for 7 days and after that it EXPIRES. When the customer pays for the software, the Admin can login to the Licensing System Admin Panel, mark the customers as PAID and the script should start working again. This is the basic idea of how the licensing system should work. ----------------------------------------- Security features: ----------------------------------------- 1) By default, The licensing system should allow only ONE installation per domain name. (if they want more than one installation, admin should be able to define it in licensing system) 2) The customers should not be able to delete any of the php files in the script (for example... [login to view URL] which checks for the license) and use it without paying for the software. If they delete any such files, the script should stop functioning. 3) They cannot register again using same email address. ----------------------------------------- Licensing System Admin section: ----------------------------------------- 1) admin can select how many records to display per page. (25, 50, 100 etc) 2) search a customer using his/her email address/name 3) admin can de-activate a user (demo user, paid user, de-activated user) 4) csv export function (name, email, website URL, date joined, other fileds) 5) Mail function - Admin can send a mass mail to users - demo users, or Paid users Or de-active Users Or ALL users.