Hardware that measures the oxidation in the MOSFETs in an IC to detect aging

Manufacturer measure to specifically log and measure produced units and keep track of them

Measure implemented in ICs to be activated only by the manufacturer, to deter illicit use

Standard cells (cells used in ICs) are redesigned to "anonymize" themselves, to be unable to be told apart

A PUF is a mechanism that generates a stable different ID for every same device without programming or storing it. It can't be reverse engineered, and even if an ID is discovered you can't clone it