He made sure of it...
A stainless steel plaque now sitting on the moon was left there by the Apollo astronauts after they landed on the surface. It's still there and will be there for a hell of a long time.
The United States Government at the time, with direct orders from President Richard Nixon, insisted that they have his name forged into the metal with his signature, immortalizing him for all eternity just below the imprint of the globe of the Planet Earth, as it was in 1969. All the Apollo landings included a plaque to be left, with two having the president's name and signature at the bottom. Unless something drastic happens like the moon drops into the ocean or collides with Mars, they will last for all eternity.
The surface of the moon is covered with a fine powder several inches thick, a concern for the first astronauts. It has been that way for time eternity. The astronauts footprints are now immortalized also, probably lasting the life of the moon.
To put this in prospective, compare the time it took to build the pyramids of Egypt and then letting them turn to dust, rebuilding them and again and letting them turn to dust, over and over a hundred thousand times as suggested by Bob Berman in his book "Secrets of the Night Sky." adding that "I am not a Crook," should have been added.
What would aliens think stumbling across this plaque a billion years from now?
They'd probably wonder, what made this human so outstanding to represent an entire, long lost civilization. He must of been something special.
A narcissist to the extreme, his name, Richard M. Nixon, the President of the United States will still be shiny and pristine, maybe buried in a couple of inches of slowly accumulating star dust, but clearly legible, if found.