Do nootropics help you in the long run? Can you take them for a period of time, stop, and still expect to see results? Or do these only work while they are in your system?

Some can yes. In order to have long term benefits from nootropics it requires you to take them for a prolonged period of time. I would suggest at least 6-12 months to make long term changes in the brain. Generally when taken for short term the effects do not last longer than their presence in your system.