How to get Android Nougat 7.0 on your Nexus 7 2013..
WARNING: When you do this you will lose all your data, so make sure you back it up...........
Also if your not on the latest version of Android (Marshmallow) this won't work, so make you sure you update to it. Then start the root process..
If your device is not rooted follow this guide, before continuing the rest of the guide.https://m.youtube.com/watch?v=WsW9upSbooM
Then after you did all that
Flash the Android 7.0 ROM
Which you can get herehttps://mega.nz/#!DQshWAYY!L_AIstrA0uLIqVAvI-GHsiUnwZt_R7RaxqNtpP9o2nI
As well as the Google appshttp://opengapps.org
Make sure you download them on your device on to your downloads folder
So first if your rooted, go to the play store and download an app called simple reboot, which will let boot into your custom recovery.
(If a pop up shows up about root access just press grant)
Then follow this guide on how to install a custom ROM or in this case the Android 7.0 Romhttp://androiding.how/how-to-install-a-custom-rom-using-twrp-recovery/
Also make sure to flash the Google apps as well..
After all that your pretty much done, you successfully installed Android Nougat on your Nexus 7 2013..
If you have any problems during the guide, comment down below and I'll be sure to help you..
The person that made the ROM..http://forum.xda-developers.com/showpost.php?p=68356872&postcount=17