AT&T Wifi Hotspot Hack-Very Easy
I found this hack in LG G2 forum at XDA, so the credit goes to whoever found this, not to me.
1. Download SQLite Editor (I have the paid version)
2. Open the file - /data/data/com.android.providers.settings/databases/settings.db
3. There's a field named 'tether_entitlement_check_state'. in System. Original value is set to 5. Changed it to 0 and save
4. Reboot the phone
5. Enjoy tethering using AT&T app, not necessary to install any other app.
Edit: USB tethering works great too.