How long could a man-made earth satellite stay up?

In article ,
Matt J. McCullar wrote:

Potentially, millions of years. The higher a satellite's orbit, the better.

However, there's one other thing to consider: the Moon. If the satellite orbit
is too close to (or in resonance with) the Moon, then the Moon will severely
perturb its orbit.

Carl Sagan tackled this topic in one of his books; I think it was _Murmurs
of Earth_. IIRC, on board one of the GOES satellites (geosynchronous Earth
orbit, which means it's thousands of miles up) is a plaque with artwork that
shows the current placement of the world's continents, as well as how we
think the same continents were positioned millions of years ago... as well
as how we think the future shifting of the continental plates will take the
land masses millions of years into the future. Potentially, anyone finding
that satellite in the far-distant future will have a rough visual idea of
when that satellite was launched.

There are plenty of spacecraft which have left Earth's influence entirely
and will never return. Some are already past all of the major planets of
the solar system and are still heading out at high speed.

True, however once a spacecraft has left the Earth's influence, it is
no longer an artificial Earth satellite but instead an artificial
minor planet. Such objects are likely to live for an extremely long
time, though.

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