Persisting your user sessions makes sure that session-related behaviors, such as user authentication, don't need to be unnecessarily repeated by the user every time your web server restarts. Adding a store is done by importing the store adapter, configuring it for your application, and providing it to express-session using the store property:

var MyExpressSessionStore = require('my-express-session-store')(storeConfig);

app.use(session({
  secret: process.env.cookieSecret,
  resave: false,
  saveUninitialized: true,
  store: MyExpressSessionStore
}));