If you’re as old as I am, you might remember Agent 99 from Get Smart. She was smart, skilled and often played a big part in righting the blunders of Agent 86, Maxwell Smart.
I imagine the owner of this license plate as an agent for good: Angel 54 driving about, helping, lifting, empowering.
Kind of makes me want to be Angel 55. Or maybe Angel #9, because 9 is a magic number.