I bought lots of monofilament line in different test strengths, years ago. Stored in a cool dry place, out of the light, it’s still good.
Same here, replaced all the line on all my reels last winter, because it was time, prices were cheap and it needed to be done, bought some new reels and spooled them up and replaced the busted, saltwater plays heck with them all!
Should be good for amother decade, lol