Felix Felicis, when you take it, your luck is to be good, and a small bottle can last 24 hours. Harry used it once to capture professor slaghorn's memory, a little bit, and in two or three hours he really succeeded in getting it, knowing that he had worked hard countless times before.
Felix Felicis, as a magic drug, can bring about so-called "good luck" mainly by improving your abilities in all aspects, such as social ability, magic ability, reaction ability, etc., so that people can feel comfortable with everything. But the preparation process of Fuling is very complex and takes half a year.
Source: @pinkeeink