long memory

noun2

1. •
   The ability to remember events that occurred a long time ago.

   • The Celtic race has a long memory, and the prospect of waging war in the insular Britain against the Saxon intruder may not have been without charms for the descendants of the Armorican exiles. — 1867
2. •
   The act or habit of holding onto a grudge or grievance for a long period of time.