LTR stands for "License To Rage". When one is in possession or is granted a License To Rage they are holder for life, and may rage whether or not the moment calls for it (but it usually does). Usually one is granted a License To Rage when there is no upcoming work, competition, or anything else that requires full attention or soberness. Holders of LTR's are encouraged to rage without limits.
Grant and Alix finished their homework, so they had an LTR.
Whoa, bro. You gotta have an LTR to get into this party.
Eli finally got his LTR. He raged for an entire week.