How do I fix the: attempt to index nil with 'PlayerId' error?

I have an error while trying to get the player/UserID when a dev product is purchased, here is my script:

local productID = 1270692852

local MPS = game:GetService('MarketplaceService')

local function processRecipet(RecieptInfo)
	
	local plr = game.Players:GetPlayerByUserId(RecieptInfo.PlayerId)
	
	if not plr  then
		-- plr probably left.
		return Enum.ProductPurchaseDecision.NotProcessedYet
	end
	
	if RecieptInfo.PurchaseId == productID then
		if plr then
			local leaderstats = plr:WaitForChild('leaderstats')
			local Gems = leaderstats:WaitForChild('Gems')
			Gems.Value = Gems.Value + 50
		end
	end

	
	return Enum.ProductPurchaseDecision.PurchaseGranted
	
end

-- call back

MPS.ProcessReceipt = processRecipet()

The error is on this line:

	local plr = game.Players:GetPlayerByUserId(RecieptInfo.PlayerId)

All of this is in a server script.

I believe it has something to do with this.

MPS.ProcessReceipt = processRecipet()

try using this instead

MPS.ProcessReceipt:Connect(processRecipet)