When you make something last or keep it going as long as you can, that's perpetuation. The perpetuation of your childhood memories is helped by looking at old photographs.
The perpetuation of a family's genes happens when people have children, and the perpetuation of oppression occurs when one dictator after another seizes control of a country's government. When something is made to last longer or is continued, some kind of perpetuation is going on. Both the noun and related verb perpetuate come from a Latin root, perpetuus, which means "continuous or universal."