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.
(..) MARTY: TERRORIST: Go! MARTY: Doc! Doc! MARTY: No! You're alive. Bulletproof vest? How did you know? What about all that talk about screwing up future events? The space-time continuum? Well, I figured, what the hell. (..)1985 Back to the Future