How to add the voice typing key to the LG keyboard on Android 6?

Here it goes:

Open Settings → Language and keyboard → LG keyboard settings and there go to keyboard height and layout, then to QWERTY keyboard layout.
There you will have option to rearrange some buttons. One of them will be settings button (a gear like button). On it will be 3 dots. Tap it and the microphone icon will show up. Just tap on it and you are good to go.

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