Backup/Export SMS from Three In Touch app? topic

I need to factory reset my phone (Samsung Galaxy S4 - Android 4.4.2 Phoenix ROM), but need to save the SMS messages from Three In Touch as I need to refer to them later. How can I backup or export these messages so that I can retain access to them following a factory reset?
I use Three In Touch exclusively for SMS as I have no signal from my normal weekday location, and none of my SMS's are being mirrored in the primary SMS app.