Yes, you should memorize them. You can make flash cards with having either the beginning and end product or the beginning and the reagent on the front side and the missing part on the back.
Keep working away, it will pay off, one of our students took the DAT today and received a perfect score in the Orgo. See the attachment. Also make sure to put time in the QR section..notice his QR score is a bit low but his science scores will more than compensate.