Membean is an excellent source to rely on when building your vocabulary for the GRE. However, to ascertain if it's a source that is enough for grooming your vocabulary for the GRE examination, we have to be sure of where you stand in terms of your knowledge.
If you have a strong vocabulary, you will have no problem learning from any source. But if your vocabulary isn't too sharp then, it's imperative that you try out as many sources as possible. This will help you to determine which source works best for you—all sources, after all, are not built to be equal.
Membean is one of the best programs that will help you in making your vocabularies for the GRE. The learning's from Membean is highly relevant to the GRE because they provide helpful tools in learning the English words that will show up in the GRE.
This program includes the definition, word components (prefixes, suffixes, and roots), little quizzes, video clips of favorite movies and TV where the particular word is used in context, memory tricks to learn how to remember the word, and word trees. It's a truly interactive and fun experience.