@Stu_The_K - I have Nodered on a Mac and as @erktrek said, you have to leave it running in the terminal. To auto-start it, you have to install PM2. See the following link for instructions - Starting Node-RED on boot : Node-RED.
Are you sure you are not doing command+c (instead of control+c)? Before I used the PM2 option, I would just minimize the terminal window and leave it running.
