Security company licensing in Pennsylvania
Pennsylvania does not license security companies at the state level, so there is no state roster and no license number for a company to show you. That is not a mark against any company operating there.
A licence is required statewide but Pennsylvania has no state security regulator and no state registry. The Private Detective Act of 1953 assigns licensing to a judge of the Court of Common Pleas in the county where the firm's principal office sits, so any roster would have to be assembled from 67 county clerks.
Pennsylvania Courts of Common Pleas (county clerk of courts) →What you can still check
There is a second license, and in Pennsylvania it may be the only one that exists: the guard’s own.
What a guard and a company should hold in Pennsylvania, and how to confirm it →