Complex sentence: It assumed jurisdiction over members of the household living within "the verge," defined as within of the King's person, wherever that might be; it was therefore an "ambulatory" court, moving around the country with the King.
Split into simpler sentences: It assumed jurisdiction over members of the household living within "the verge," defined as within of the King's person, wherever that might be. This means it was an ambulatory court, moving around the country with the King.