Learning drugs could vastly improve memory, but however was dangerous and illegal under Space Corps Directives. They could also cause the user to remember nothing but irrelevant information
Red Dwarf Second Technician Arnold Rimmer once spent several weeks preparing a revision timetable for his engineers exam, however only actually leaving himself one evening to actually do the revision. On the night in question, Rimmer took the leaning drugs but couldn't find the timetable. Rimmer went down to the disco to look for Dave Lister, who admitted to spilling goat vindaloo down it. All Rimmer remembered was the conversation he had with a mocking Lister and his drinking buddies Olaf Petersen, Selby and Chen.
Three million years later, Lister attempted a chef's exam to outrank Rimmer and replace him as ship's hologram with his old crush, Kochanski. Lister took learning drugs for the exam, and Rimmer threatened to reprimand him for it until Lister said that he'd got them from Rimmer's locker. ("Balance of Power", Series I)