Hilchot Berachot 4:1-2 (Saying Birkat HaMazon away from where you ate)
12:36 pm
If a person says Birkat HaMazon in a place other than where he ate, has he fulfilled his obligation? What about Me’ein Shalosh (aka Al HaMichyah)? What should he do if he isn’t sure whether he said HaMotzi?