Most Membean plans have more than 1500 words in total. Retaining knowledge of all the words in the list takes commitment via short but focused daily training sessions.
We have chosen our words very carefully by rigorously analyzing past exams and carefully combing many different vocabulary lists. We also arrange words in a specific order to maximize subject/root/part-of-speech diversity.
Please remember that it's OK to not get through all of the words in Membean. Do the best that you can. We have some training guidelines here: http://membean.com/tours/user.
The key to working with Membean is consistency. Keep your sessions short, space them apart, and you will do well on the verbal portion of the test!