How i can set max grow on Player? My script not work...

It would seem that you reset your debounce inside the elseif section. Debounce should be reset outside the if elseif else end section.

replicatedStorage.Simulator.Test.OnServerEvent:Connect(function(player)

	if not remoteData:FindFirstChild(player.Name) then return "NoFolder" end

	local debounce = remoteData[player.Name].Debounce

	if not debounce.Value then

		debounce.Value = true

		if player.leaderstats.Power.Value < 3000 then

			player.leaderstats.Power.Value = player.leaderstats.Power.Value + 1 * (player.leaderstats.Rebirths.Value + 1)

			player.leaderstats.Money.Value = player.leaderstats.Money.Value + math.random(1,4) * (player.leaderstats.Rebirths.Value + 1)

		elseif player.leaderstats.Power.Value >= 3000 then

			player.leaderstats.Power.Value = player.leaderstats.Power.Value + 0 --this line is not necessary, but you may want to leave it for clarity

			player.leaderstats.Money.Value = player.leaderstats.Money.Value + math.random(1,4) * (player.leaderstats.Rebirths.Value + 1)

		else --this else is not needed

		end

		--move this two lines
		wait(cooldown)
        	debounce.Value = false

	end

end)

Have a nice scripting session!