How can I store a variable on a player?

[Metamorphics]

AddCSLuaFile( "cl_init.lua" ) -- Make sure clientside
AddCSLuaFile( "shared.lua" )  -- and shared scripts are sent.
 
include('shared.lua')



function ENT:Initialize()
 
	self:SetModel( "models/entities/syringe_out.mdl" )
	self:PhysicsInit( SOLID_VPHYSICS )      -- Make us work with physics,
	self:SetMoveType( MOVETYPE_VPHYSICS )   -- after all, gmod is a physics
	self:SetSolid( SOLID_VPHYSICS )         -- Toolbox
 
        local phys = self:GetPhysicsObject()
	if (phys:IsValid()) then
		phys:Wake()
	end
end
 
function ENT:Use( activator, caller )
	local ply = activator
    if(!ply:IsPlayer()) then 
		return
	else
		ply:Give("weapon_dc_speedster_v9")
		ply:SelectWeapon("weapon_dc_speedster_v9")
		self:Remove()
	end	
end
 
function ENT:Think()
	
end

I want to make it so after 4 times a person uses the entity they will die. I would also like the amount of uses to reset to 0 after somebody dies. (Without using global variables)

[man with hat]

[lua]ply.variable = value[/lua]

[Metamorphics]

[QUOTE=man with hat;50012938][lua]ply.variable = value[/lua][/QUOTE]
Ok thanks