Which is right?
2335/6 - 2371
Lore was activated around 2335 or 2336, but was shut down by Soong shortly afterward because the colonists at Omicron Theta viewed Lore as a threat.
Starbase 295: The Enterprise-D headed to Starbase 295 after encountering the self-aware Borg in 2370. ("Decent, Part II" [TNG])
He was finally destroyed (irreparably) in 2371 when the Enterprise crash-landed on Veridian III at the end of Star Trek: Generations