I have recently been working on data storing system via module script, which can be required from any server script. However, I came across with this problem which I can't solve it because I have little knowledge about modules. If you see any problems with my script or have any suggestion, I am always open for it. Thank you for any helps 

--module script
local playerData = {}
return playerData

--serverscript
local MPS = game:GetService("MarketPlaceService")
local plrData = require(script.Parent.ModuleScript)
local shopData =  require(script.Parent.ModuleScript2)
local remote = game.ReplicatedStorage.buyRemote


function completePurchase(plr,id)
	local item = --iterate shopData to find the item 
	if plr and item then
		local customerData - plrData[plr.UserId]
		customerData["cash"] = customerData["cash"] + item["GivingValue"]
	end
end
function purchaseRequest(plr,item)
	if plr then
		local item = shopData[item]
		if item then
			MPS:PromptProductPurchase(plr,item["ProductId"])
		end
	end
end

function proccessRecipit(plr,id)
	local player = game.Players:GetPlayerByUserId(plr)
	if not player then 	
		return Enum.ProductPurchaseDecision.NotProccessedYet
	end
	completePurchase(player,id)
	return Enum.ProductPurchaseDecision.PurchaseGranted
end
	
MPS.ProccessRecipit = proccessRecipit	
remote.OnServerInvoke = purchaseRequest
Anonymous