How can one implement Stripe Relay API (or any 3rd-party API) with Laravel 5.1?

I was looking at Laravel Cashier to implement a payment system for my client's website, but I couldn't figure out a way to use Cashier without it being for subscriptions-- unless I'm wrong, in which case, please feel free to correct me.

By exploring Stripe's website, I stumbled upon the Relay API, which allows me to sell products (or services for that matter). That's exactly what could fulfill my client's requirements. But I don't understand how I can link the Relay API, or any other 3rd-party API for that matter, to Laravel 5.1.

So how does one go about to implement those kinds of APIs with Laravel 5.1?

via Chebli Mohamed