Some ways of strengthening one's memory include: Keeping away from sin, because the bad effects of sin result in a bad memory and the inability to retain knowledge. Frequently remembering Allaah, may He
be glorified, by reciting dhikr, tasbeeh (saying 'Subhan Allaah'),tahmeed ('Al-hamdu Lillaah'), tahleel ('Laa ilaaha ill-Allaah') and takbeer ('Allaahu akbar'), etc. Allaah says (interpretation of the
meaning): "...And remember your Lord when you forget..." [al-Kahf 18:24]. Not eating too much, because eating too much makes one sleep too much and become lazy, and it dulls the senses, besides exposing one to the risk of physical diseases. Most of the diseases which we see result from food and drink. Some of the scholars have mentioned certain foods which increase the memory, such as drinking honey and eating raisins
and chewing certain kinds of gum resin. Another thing that can help the memory and reduce forgetfulness is cupping (hijaamah) of the head, as is well known from experience. (For more information see Al-Tibb al-Nabawi by Ibn al-Qayyim). And Allaah knows best. ..