game.Players.PlayerAdded:connect(function(Player)
local Head = Player.Character:WaitForChild("Head")
if Head then
if game:GetService("GamePassService"):PlayerHasPass(Player, 351377310) then
local FireEffect = Instance.new("Fire", Head)
FireEffect.Heat = 9
FireEffect.Size = 5
FireEffect.Colour = Color3.new(236/255, 139/255, 70/255)
FireEffect.Colour = Color3.new(139/255, 80/255, 55/255)
end
end
end)
Something to do with the character/player! Im not sure where though, please inform me.

2 comments
Output errors?
Also, on line two instead of using wait for child use find fist child. That way if there is no head it won't wait forever for the head to exist. Just a little thing.