OnePlus works on Android 7.0 Update 3 for OnePlus One OnePlus now that was launched two years ago found in the reference list runs on Android 7.0 Build nougats. You can not officially available for OnePlus One
One reason to believe that the nougat not be available for the phone to do with the play date chips that animates it. The Snapdragon 801 SoC is a few generations old, and is known to feed the old flagship models like the HTC One (M8) and LG G3. Android 7.0 is to test the phone is an official release.Taken the AOSP source updateing XDA member, almost everything worked in the ROM at the time, except for the video camera and a keyboard available.
OnePlus one has a 5.5-inch (1920 × 1080 pixels) Full HD display with Corning Gorilla Glass 3 protection powered by a Snapdragon 801 quad-core processor 2.5 GHz (MSM8974AC) with 3GB of RAM and 16GB / 64 GB of storage. with rear camera 13MP camera with dual LED flash, Sony Exmor BSI sensor, f / 2.0 aperture, 4K video recording and connectivity options before the 5 megapixel camera includes 4G LTE / 3G, Wi-Fi 802.11 ac (2.4 / 5GHz) Wi-Fi Direct, Bluetooth 4.1, GPS, NFC. Packaged by 3100 mAh battery.
OnePlus One will not be officially updated beyond the current construction of marshmallow.