I am probably going to take it for the rest of my life as a maintenance, but I suppose that if one were to live a very "alkaline" lifestyle, mostly raw foods, vegetables, lots of pure water and sunshine, then the body becomes strong enough to keep its own terrain free of all critters.
The problems arise, after we become alkaline inside, when we overindulge at a party, or on vacation, or when we go through periods of intense stress, grief, etc... These things all promote acidity, which in turn fosters the re-growth of the critters ...
It would be a personal choice whether to continue taking it or not. But I for one am never going to be without in my house at least.