As an Android user, I liked my Nexus 7 at the time, but I received security updates for a year or two max, and then never bought an Android tablet again because of it.
I still have some iPad 2's floating around, which have the same issue, albeit on a longer scale. Can no longer update the OS, most new apps won't install as they target a different OS, it _seems_ to be getting more sluggish over time (though there was a clear performance drop between two of the major OS versions - I think it was 6 to 7). It's a shame as it's still a useful and nice piece of hardware.
If it's a 2013 WiFi version (a mostly great device): https://wiki.postmarketos.org/wiki/Google_Nexus_7_2013_(asus...