Mmm 17 views and no answer - I guess its more google
The title is quite vague. Which is probably why you got as many views as you did. Members often refrain from responding to questions that have been asked/answered quite possibly hundreds of times and particularly when a simple search will reveal the answer(s). I believe in the section area nootropics, there are links under resources which provide again, the answers.
FTR: it appears it's an individual task to determine what, if any amount works for you. It's water soluble so you can take it between meals, but with meals it appears (iirc) a bit better - like 20%.
From past research, which may be faulty now, I think 98% of piractam leaves you body via urine. That is, once you establish a proper intake, if you can that is, you can drink you urine regularly and you should not ever have to purchase piracatam again.