I've been using the extension for well over a year and there are no saved permissions except the last one I granted.
Nos2x Firefox.
Discussion
That's broken, you should update to nos2x 2.0
It's Chromium only though. On Firefox you should probably use nos2x-fox or some other that is listed on https://nips.be/7
You should get the latest version. The project forked, so ...