So 'you must be right because you Google'd for it' - whilst me who has been using NPP every day of the week since 2007-ish, must be wrong
I suspect the PI referenced was called Autosave or Autosave 2 - no idea what they do, because I don't use them. Never knew they existed until I just looked in the NPP Plugin Manager. Like some other 'widely used' software, NPP seems to be overburdened with overlapping, redundant PIs.
Right now I don't have any files open in NPP - number of snapshots in its auto-save folder - precisely ZERO. If I open a file now, and edit it progressively over the next four days, (including system shut downs each evening), then on Friday at noon, I would be be able to get back to where I was at 10pm this evening - assuming I never did a Save of the file between now and then.
I am not sure if that is what Notjohn has in mind - its nigh 30 years since I used Wordstar.
BR