The Android N Developer Preview 4 was released earlier this afternoon and now those registered in the Android Beta program are seeing the OTA come to their devices. The update brings build NPD56N to your Nexus device and weighs in at a lightweight 168MB. The update brings all of the fixes and enhancements to the beta that I outlined earlier and, of course, brings the final API set to the device.
If you have a device registered in the Android Beta program, you can go to your device and check for the update manually by going to Settings>About Phone>System Updates and check for the
update. In my case I have received the update on both my Nexus 6 and my Nexus 9 tablet (I am running Marshmallow on my Nexus 6P as it is my daily driver) and both updates went very quick and smooth.
If you have a Nexus device (or select Sony Xperia Z3’s) you can register your device for the beta by going to the Android Beta site and registering your device. Doing so will automatically download N to the device so you can start using it and testing it. Keep in mind that the software is beta. That means you will likely run into bugs or issues. You can get out of the beta at any time by revisiting the beta site and un-registering your device. Doing this, however, will completely wipe your phone so make sure you have any local files or photos backed up.