Comment by shiroiushi

I did say "offhand"; I'm not personally familiar with npm. There is some stuff like this in Linux-land if you know where to look, of course, such as the message in Vim, but even there you only see it if you start the program without any filename argument, or look in the docs, so it's hard to call that "nagware", which usually means something that won't allow you to use the software without first reading and acknowledging the advertisement.