When the Metal Method was first created, the heart of the course was the Metal Licks Lesson. It actually was the metal method. The metal method is a technique developed for memorizing licks, and even more important, recalling them while improvising. In 1982 I was giving private guitar lessons and knew about sixty different songs. I took every lead from these songs and divided them into 136 licks.
Licks are short melodic lead phrases.
Then I took all of the licks and transposed them to the key of A. That way if the lead was in G, for instance, which is two frets lower than A, I could move all 136 licks back two frets and they would be in the correct key. Next, I organized the licks according to their first note. Memorize and practice all licks with the first note of each lick in mind. It's a way to organize the 136 licks into small, easy to memorize sections. For example you may know five licks that begins on the first string fifth fret.