General concensus is that Cycle is pretty much useless. First, the bacteria they say are in the bottle aren't the proper bacteria to cycle a tank. Second, most people believe that there is no way that the bacteria could survive the extreme heat the products (Cycle, Stress Zyme among other "bacteria in a bottle" products) encounter while being shipped in trucks (insides of trailers in summer months can easily reach 120F or more) and stored in warehouses that can be equally as hot.
And once your tank is cycled, you indeed do not need any more cycling aids. Once the bacteris is there, it will remain there unless something happens to kill it off.