The Nexus 6P was released on the 1 September 2015^[1], which marks the beginning of its update period. On the 6 August 2018, the Android 9 was released, a next version of the operating system, which not made available for the Nexus 6P, thus leaving Nexus 6P on the the previous version of the operating system, the Android 8. This date marks the end of what we consider its update lifetime.

These two dates are 2 full years and 11 full months apart, which gives it C- tier.