I'm doubtful that certificate means much of anything now, but someday maybe? Depends how much of a following the American series gathers. If someday they are as coveted as Model 19 Combat Magnums you'll be glad you kept that little piece of paper and whatever other trinkets it shipped with.
Ruger ofter includes some novelty item with it's gun. I've seen stickers, cleaning cloths, and nice padlocks for my shed