Not sure what the round file is but if it's a waste bin then this might be the correct place for it eventually but only after you give the paper a try. I might be misquoting him but I thought PE has said that paper should be good for at least 5 years, after which it will presumably deteriorate at a speed which is unknown

I got some Supra III when I bought my CPE2 and I suspect it was probably 5 years old. It seemed fine to me. I cannot say it was as good as new as I had never had new Supra III paper but it was certainly usable