NEM is a peer-to-peer crypto & blockchain project launched in March 2015. It was started by a Bitcoin Talk forum user who drew inspiration from Nxt. However, NEM is not an Nxt fork, but it has its codebase, written in Java. It’s a community-oriented coin where participants were recruited on the same forum.
In 2018, NEM fell victim to a hacking attack where 532 million XEM coins (worth $400 million at that time) were lost to hackers. However, the NEM community started tagging them automatically and they collected enough info to provide to law enforcement.
Your first step is to register a NOWPayments account. After that, you will see that integrating a NEM payment gateway is as simple as copying a chunk of HTML code to your website.