How do I call any payment gateway by clicking on the button

Hi,

Could anyone please help me in figuring out a way to include a payment gateway (from any payment gateway - even one would be sufficient) in my game.

I want to buy the business edition, but for my company, it is very important for the game to be made publicly available but in PAID form. I want this tool to be included in my company.

NOTE: clay.io is claiming to include this feature...could now anyone tell me how it can be done?????????

Thanks in advance.