pm2 is just a process scheduler which runs on Node.JS, so depending on your Node.JS version, you can use certain ES6 features (Node.JS LTS (v6) can run nearly all), like const , let , class , arrow functions, template literals, default parameter values, destructuring assignments, etc. import is one of the few ones which does not work, yet. It is pending implementation in the JavaScript VM (Google's V8)
The OP most likely uses Babel or similar in Grunt to transform import to require , which is absolutely not how the new feature works, but the only way to make it run somehow in the current Node.JS