Manufacturers make vinpocetine from compounds found in the periwinkle plant (Vinca minor). A few people take it hoping to sharpen memory or focus, but solid human evidence for those goals does not exist. Most medical bodies do not list it as a proved memory aid.
Take it with food. Vinpocetine can thin the blood and drop blood pressure. Anyone with a bleeding condition, low blood pressure, or a surgery date should stop use and speak with a doctor first.
Marketed doses often fall between 5 and 30 mg per day. The long safety record in healthy people is thin, so using the lowest dose that makes sense is the sensible path.