API development for Extension installation upgradw process

Looking for API development Extension installation and upgrade process: We develop multiply shoppingcart ( magento, opencart, wordpress, joomla, virtuemart, moodle, prestashop etc) modules for somany payment gateway companies. some are free for merchants, some are paid. for free module- PG company take module and distrubute it to their merchants, there have a script which send the domain name to our database to understand which domain is using our module and that is in encrypted code. so no one can understand we are knowing who are using our module but now we have facing problem due to encryption, it is not work seamless without loader. so we have to publish source code to PG company but we don't want to provide complete code to PG company, but want such API which install complete code in merchant server with any help of any another module. so we can provide that module to PG company. once it is installed it will ask for complete installation by a click so it will syncronize with my server latest module and import the other's required files and update it's domain details in my db with module name, time etc and once latest module is come out then user will get a alert for it. Presently we are using this code for OpenCart module, code become change but logic same. but we don't want to use it. we don't want anyone can understand what we are doing......and if they remove that API code then module shouldn't work. For free module. 1. some minimum module will install in merchant site and and later by a click it will contact with our server and complete tha installation by importing others files and create module details, ( version, shopping cart name, date, domain name, payment gateway name etc) this work will done from our server site. 2. show alert message if updated module is available, if we want to show them any message. 3. module shouldn't work if API code is removed 4. this API script should work with any extension's seamless installation, upgradation and push notification ( alert for module upgrade). For paid module.... 1. as your present API 2. main domain and test domain 3. for test domain we can set the time limit like 3 days, 15 days,30 days and as well as main domain. 4. test domain must be in sub folder or in sub-domain 5. module shouldn't work if API code is removed. 6. Licence key can be changed from API admin. 7. and if you think some modified features you are open to add.