What version of [insert npm module here] do I have?

I'm picking up a project I had in Node.js. It worked fine but it didn't go to production because lacking time.

I updated node, express and socket io with

npm update [package name] -g

I know that -g states for global but I'm not sure if I installed in this way on the server so, my questions are:

How do I know which version my app has?

If I need to update just for that app, how should I proceed?