After five years, you'll be fully 'vested' in the company pension plan. [=you will have earned the right to get a full pension when you retire]
Congress is 'vested' with the power to declare war. = The power to declare war is 'vested' in Congress.
She has a 'vested interest' in seeing the business sold, as she'll make a profit from the sale.
(..) ...and the specific circumstances of how, where, and when... ...young Biff got his hands on that . I'll ask him. Bulletproof vest! Great flick! Great frigging flick! What the hell's going... - What the hell are you doing in here? - Party's over, Biff. MARTY: Sorry, ladies. (..)1989 Back to the Future Part II