464.500 is such a common itinerant business frequency that trying to find the user via the FCC database would be somewhat akin to trying to find a needle in a haystack.
Best thing you can do is listen and take notes. If this freq/tone combo continues to see use for more than a few days, you can probably figure that it's a local user and not out-of-towners using the radios in your area temporarily. Do operations seem to be facility-based (i.e. school, hospital, retail, industrial, etc.) or is this a wide-area operation? Repeater output or simplex? With enough clues, you'll likely be able to determine who this user is.
Best of luck, and please let us know if you figure out who this user is!