Aliens have been visiting us for an eternity, and when they noticed that civilised society was emerging, they launched the nano historians – flying nanobots smaller than dust that are attached to (as in follows) every human from birth until death. The historians take 360 degree images, record sounds and smells, and transmit them to the motherships. The motherships are, of course, not something humans can detect.
Then in 2026, the aliens made the data available, to humans, for a price, or to the highest bidder. Mysteries like the assassination of JFK could be solved. Prisoners could be freed. Illicit affairs made public. As well as more mundane things, like revisiting happy memories, or the adventures of loved ones who are long gone.
Before releasing the videos of the past, the aliens determine the worth, using their own intelligence, and also how many people are interested. Some, they decide, are not for sale. Some, they decide, could be made into movies. Some, they decide, can be used for blackmail.
Before long the aliens are easily the richest and most powerful “people” in the world, and then their real plan emerges…
Meanwhile our hero is a hacker type who specialises in acquiring memories that the aliens think are low value, then reselling them to buyers he finds. In doing so he gains some leverages of his own, and teaming up with others in the same game, leads the war against the aliens.