I am in NJ and found that I have a small claims judgment against me in Indiana. It is from 2011. How long does this remain open?

Forever.
It's only billing that has a SOL. Once someone goes to court and gets a judgment, it's good forever.

I had a friend who chased down someone he won a judgement against for 30+ years and finally got it from the guys estate when he died...The Judgement is forever..the writ can be renewed from time to time indefinitely.

... it's good forever.

No, actually in many states (if not all), it is only good for so many years, and possibly may be renewed then. I don't know what the period may be in Indiana.

Even if it has to be renewed, they can, so it could remain forever.

So pay it. Otherwise it will always be there.