The Nexus 6 was released on the 1 November 2014^[1], which marks the beginning of its update period. On the 21 August 2017, the Android 8 was released, a next version of the operating system, which not made available for the Nexus 6, thus leaving Nexus 6 on the the previous version of the operating system, the Android 7. This date marks the end of what we consider its update lifetime.

These two dates are 2 full years and 10 full months apart, which gives it F tier.