A company spokesperson informed Android Police that a software update including Nougat, the latest version of Android, will roll out to Google’s 2014 Nexus devices “in the coming weeks.” It’s possible that the software update was delayed for both devices because of serious bugs hindering the user experience.
Until then, you can enroll in the Android Beta Program that puts you at the front of the line to get software updates. This is why I already have Nougat on my Nexus 9 LTE. It should instantly move you to Nougat on your phone or tablet, too.
Source: Android Police