AFAIK items that "drop" as "loot" should persist so long as there are some player-made structures nearby. I've never had any such item despawn on me... but I wouldn't leave them lying around forever if they matter to you, just in case.

Pretty new here so might be wrong but I believe as long as there is a workbench nearby they should not disappear.

Without a workbench, stuff despawn in 2 hs i believe