Build Stripe subscriptions into your website in minutes.

 https://www.pricewell.io/

Another mechanism to facilitate website subscriptions. 

Payment Processing 101: What’s the Difference Between a Payment Processor, Payment Gateway & Merchant Account?

https://ecommerce-platforms.com/ecommerce-selling-advice/what-is-difference-between-a-payment-gateway-payment-processor-and-a-merchant-account
Good walkthrough.

Amazon Offers Retailers Discounts to Adopt Payment System

https://www.bloomberg.com/news/articles/2018-05-02/amazon-said-to-offer-retailers-discounts-to-adopt-payment-system
Amazon's upping their game against PayPal and Stripe.

The Best Online Credit Card Payment Processing Services for Your Business

https://zapier.com/blog/best-payment-gateways/
Comparison of #ecommerce payment options, with best-of-breed for different categories. 

Square Credit Card processing & business solutions

https://squareup.com/

Wow! Square isn't just a smartphone #creditcard reader anymore. They're a full-fledged #ecommerce and #POS vendor: