How long do dwarf stars live?

How long stars live depends primarily on their mass. Low mass stars live longer.

A yellow dwarf star like the Sun has an expected lifetime of about 10 billion years on the main sequence, followed by a "red giant" phase that is considerably shorter, followed by a "white dwarf" (Type VII) phase lasting a very, very, very long time before the star eventually cools to the point it no longer emits light in the visible range, becoming a "black dwarf".

Low-mass red dwarfs (below, say, 0.25 stellar masses) could conceivably live trillions of years. We don't really know exactly what will happen to them or how long they will live, because the universe itself is only about 14 billion years old, not nearly long enough for any red dwarfs to have died.