LG G6 now comes with 1 extra year of warranty for free (US only)28
If you've bought your G6 before today (June 15, 2017), you'll have to register within 12 months of purchase, and provide a proof of purchase, plus your phone's IMEI/MEID and serial number. If you're getting an LG G6 today, or after today, you'll have to register within 90 days of purchase. Registrations can be made via a special LG web page that's online as of today - see the first source link below.
If you register for LG's new program, you'll be "entitled to a free replacement of a qualified LG G6 which fails due to manufacturer defect in material or workmanship." In other words, if your G6 gets damaged and it's not your fault (as in: you didn't drop it or anything like that), LG should replace the phone for free - "within two business days."
Usually, smartphones come with 1 year limited warranties in the US, so it's obviously nice to see that LG is offering an extra year of warranty - for free - to G6 owners.
sources: LG, Press release