—Outsourcing the fabrication of semiconductor devices to merchant foundries raises some issues concerning the IP protection of the design. Active hardware metering schemes try to counter piracy of integrated circuits by enforcing the fabrication plant to run an activation protocol with the IP owner for every chip that is produced. In this work, we analyze the protocols of two active hardware metering schemes that were recently proposed by Roy et al. in [1], [2]. We study how these schemes achieve security and based on this, we suggest more efficient and secure versions for both. Finally, we present a simplified and secure activation protocol based on physically unclonable functions.