how do I get tools to save after you leave or die?

I'm making a simulator game and I want to make it so you don't have to buy an item again after you die or leave. I've looking all the over the internet and I can't seem to find anything that works

(I may be wrong I'm new to scripting) You would need a value to assign a person a tool and after you have that value you can just datastore, for example:

--//DataStore (I'm too lazy to do it but here take this :p)
game.Players.PlayerAddded:Connect(function(plr)
	local stats = Instance.new("Folder", plr)
	stats.Name = "Stats"

	local knife = Instance.new("StringValue", stats)
	knife.Name = "Knife"
	knife.Value = "N/A"
	--//DataStorage Goes Here
end
--//Check Tool
game.Players.PlayerAdded:Connect(function(plr)
	if player.Stats.Tool.Value == "BoxKnife" then
		local boxknife = game.ServerStorage.Tools.BoxKnife
		boxknife.Parent = game.StarterPack
	end
end
--//GiveTool(Lets say you buy them by pressing a button)
script.Parent.MouseButton1Click:Connect(function(plr)
	script.Parent.Text = "BOUGHT"
	plr.Stats.Knife.Value = "BoxKnife"
end

Something Like This (I thought of that in half a minute)