"One simple charm later and your memory will be restored to its natural range and vigour."
-- advertisement in the Daily Prophet (DP4)
No word on whether the Mnemosyne Clinic will help you forget things you'd rather not remember, or - alas - their location, though Diagon Alley is probably a fairly safe assumption (DP4).
Mnemosyne was the Greek goddess of memory and the mother of the nine Muses (Wikipedia).
Although the date printed on the fourth Daily Prophet Newsletter (DP4) is 1 October 1999, the timeframe for this event is 1992-1993.