How can I make my shop better and exploit-free?

Keep in mind that I'm a beginner at developing roblox games and have started to understand how codes work generally.

In my game: one of the major parts of the game is to make the shop system efficient and secure. Of course I have to make all features secure.

So far I've come up with this kind of shop system. In which the purchase event runs with the button(Currently this works for coins only. I haven't made the system check what kind of currency is going to be used yet)

When the buy button is pressed, the display price(display is supported with Ui with a script designed for the shop system itself. This menas there's going to be many scripts) is going to be subtracted from the players price. If the player doesn't have enough coins, a frame will pop up telling them. Else, It's going to do as the code does. After that, the corresponding item Ui with a script designed for the equipment system will be cloned to the weapon equipment scrolling frame.

It also comes with an addition of telling if the player has bought the item. I used a folder to make sure that everything which was bought is going to the specific folder.

(localscript)

-- Player vars

local Player = game.Players.LocalPlayer
local leaderboard = Player:WaitForChild("leaderstats")

-- services
local RS = game:GetService("ReplicatedStorage")

-- Events 
local EFolder = game.ReplicatedStorage:WaitForChild("EventsFolder")-- Brings the folder
local CPurchase = EFolder:WaitForChild("CoinsPurchase")
local OweItem = EFolder:WaitForChild("OwnedItem")
local Affordable = EFolder:WaitForChild("OwnedItem")


-- Buttons and item data
local button = script.Parent
local price = script.Parent.Parent.Price
local thisName = script.Parent.Parent.ItemNameview
local Purchased = script.Parent.Parent.PurchasedLabel

-- CheckItemsOwned folder 
local BoughtItems = game.ReplicatedStorage.BoughtItems


-- Purchase
button.MouseButton1Click:Connect(function()
	game.ReplicatedStorage.EventsFolder.CoinsPurchase:FireServer()
	
	if leaderboard.Coins.Value >= price.Value then
		leaderboard.Coins.Value = leaderboard.Coins.Value - price.Value
		local RSItem = RS:WaitForChild(thisName.Text)
		RSItem:Clone().Parent = BoughtItems
		local ThisUI = game.ReplicatedStorage.UIStore:WaitForChild(thisName.Text)
		local WeaponEquipment = Player.PlayerGui.Navigations.EquipmentFrame.WeaponsScroller
		ThisUI:Clone().Parent = WeaponEquipment
	end
	
	if BoughtItems:FindFirstChild(thisName.Text) then -- Check if the item is owned/purchased
		button.Visible = false
		Purchased.Visible = true
	else
		button.Visible = true
		Purchased.Visible = false	
	end
	
	if leaderboard.Coins.Value < price.Value then
		Player.PlayerGui.Navigations.ShopFrame.InsufficientDisplay.Visible = true
	end	
end)

Here comes the part which I haven't fully understood yet. Using the remoteevents. From what I understand, I have to set up a condition, which in this case is when I press the purchase button. When that condition triggers, I have to tell the remote event what to do. I think whatever code I write in the onserverevent is what I code I want to become legit. Do I think right?

-- folder
local EFolder = game.ReplicatedStorage.EventsFolder

-- services
local RS = game:GetService("ReplicatedStorage")

-- events
local CPurchase = EFolder.CoinsPurchase
local GPurchase = EFolder.GemsPurchase

-- functions

CPurchase.OnServerEvent:Connect(function(player) -- event for CPurchase
	print("event fired")	
	local Player = game.Players.LocalPlayer
	repeat wait() until Player
	local leaderboard = Player:WaitForChild("leaderstats")
	local price = Player.PlayerGui.Navigations.ShopFrame.ShopPreviewFrame.Price
	local thisName = Player.PlayerGui.Navigations.ShopFrame.ShopPreviewFrame.ItemNameview
	local BoughtItems = game.ReplicatedStorage.BoughtItems
	local button = Player.PlayerGui.Navigations.ShopFrame.ShopPreviewFrame.BuyButton
	local Purchased = Player.PlayerGui.Navigations.ShopFrame.ShopPreviewFrame.PurchasedLabel


	if leaderboard.Coins.Value >= price.Value then
		leaderboard.Coins.Value = leaderboard.Coins.Value - price.Value
		local RSItem = RS:WaitForChild(thisName.Text)
		RSItem:Clone().Parent = BoughtItems
		local ThisUI = game.ReplicatedStorage.UIStore:WaitForChild(thisName.Text)
		local WeaponEquipment = game.Players.LocalPlayer.PlayerGui.Navigations.EquipmentFrame.WeaponsScroller
		ThisUI:Clone().Parent = WeaponEquipment
	end
	
	if BoughtItems:FindFirstChild(thisName.Text) then
		button.Visible = false
		Purchased.Visible = true
	else
		button.Visible = true
		Purchased.Visible = false	
	end
	
	if leaderboard.Coins.Value < price.Value then
		game.StarterGui.Navigations.ShopFrame.InsufficientDisplay.Visible = true
	end	
end)

Is there any way to improve the whole entire thing? Leave comments below.

I think it is fine but your money system could be upgraded using gui's and making the whole money function in a gui

tl;dr

Understanding the concept of the title, I'm assuming you don't want your shop freely exploited.

There are two simple solutions for this.

(PLEASE NOTE I DID NOT READ ALL OF YOUR POST)

1. Filtering enabled - this blocks all client to server communication vice versa unless granted through a key for example, a remoteevent.

2. Be specific, if you don't want people to take items out of your store through scripts then make a check function so that when they're granted with the item you check there cash/currency to see if it has changed.

2.5. Put a cap on currency, if their cash magically went up 50k or more then you can add a script for that. give them a punishment/add them to a banlist, really anything you want to do.