It's not about enhancing memory or attention, although it might be a side-effect. Meditation is better for that. Lojong is a Mahayana Buddhist practice aimed to re-orient your basic outlook, intentions and attitudes in life and prepare you. It consists of 59 aphorisms which are attitudes in themselves with various explanations spanning pages throughout the centuries (like bible verses). They are grouped in 7 categories or factors. A few of them you probably know already.

Slogan 13. Be grateful to everyone. Slogan 22. If you can practice even when distracted, you are well trained. Slogan 29. Abandon poisonous food. Slogan 35. Don't try to be the fastest -- Don't compete with others. Slogan 36. Don't act with a twist -- Do good deeds without scheming about benefiting yourself. Slogan 37. Don't turn gods into demons -- Don't use these slogans or your spirituality to increase your self-absorption Slogan 56. Don't wallow in self-pity. Slogan 57. Don't be jealous. Slogan 59. Don't expect applause. etc.

Supposedly it took the one writing it down more then a decade to master them all. You can read more about them in the links I provided or the wikipedia. https://en.wikipedia.org/wiki/Lojong