The LG G3 was a pretty good phone when it was released in 2014. It had a Snapdragon 801 processor, a 5.5" 1440p display, 3GB of RAM, and a 3,000mAh removable battery. I expect the number of people still using the G3 in 2017 is pretty small, but if you're still hanging in there (and you're on T-Mobile), you have an update waiting for you.
It's not often that an Android phone is updated three years after release, but T-Mobile has just pushed 'Software version D85130g' to the G3. The new version includes a more recent security patch (the page doesn't specify the exact patch level), as well as bug fixes for 2G/3G roaming and the included LG app. It's still running Android 6.0.1, but that's probably to be expected.
The update should be available to all G3 owners on T-Mobile. It clocks in at 132MB, and requires 50% or higher battery life to install. You can find more information at the source link below.