Spark

The Spark is a combination of a Transformer's mind and soul into a single semi-organic energy-based entity. In many ways, Transformer bodies are really just shells housing their essence -- a Transformer can have its parts replaced endlessly as long as its Spark still operates.

This in turn means Transformers live for millennia, and have different view on the passage of time. Likely Transformers can spend thousands of years doing essentially the identical routine cycle after cycle with little change.

The Transformers universe has many stories relating to Sparks.