Hello, I want to make a part that can change speeds, but I only want it to actually change the speed if a user owns a specific game pass. Im kinda new so any help is appreciated thanks!

Sources

MarketplaceplaceService

StarterCharacterScripts

WaitForChild

Functions

Differences between local and server scripts

Script (LOCAL SCRIPT)

local MS = game:GetService("MarketplaceService")
local GamepassID = 1234 -- whatever the gamepass' id is.

local Char = script.Parent -- when referencing the character we only need to use script.Parent, as the script only runs as soon as it's parented into the character.
local Hum = Char:WaitForChild("Humanoid") -- we need this to change speed.
local User = game:GetService("Players"):GetPlayerFromCharacter(Char) -- this is needed as we need their UserId for MarketplaceService.

if MS:UserOwnsGamePassAsync(User.UserId, GamepassID) then
	Hum.WalkSpeed = 25 --whatever the walkspeed will be.
end

If this has helped you, please mark this answer as the one that helped you!

local id = 111 -- Your Gamepass Id Here
local m = game:GetService('MarketplaceService')
	 
	game.Players.ChildAdded:Connect(function(player)
	     player.CharacterAdded:Connect(function(char)
	          if m:UserOwnsGamePassAsync(player.UserId, id) then
               local h = char:WaitForChild('Humanoid')
	               h.WalkSpeed = 32
	        end
	  end)
end)

Put that script on StarterGui

local ID = 123 --Put your Gamepass ID
local Marketplaceservice = game:GetService("MarketplaceService")
local Player = script.Parent.Parent
local Humanoid = Player.Character.Humanoid

while wait() do
	if Marketplaceservice:UserOwnsGamePassAsync(Player.UserID, ID) then
		Humanoid.WalkSpeed = 32 --Default is 16
	end
end