A flexible package having a tamper evident product authentication label secured thereto and methods of making the same are provided. The package includes at least one panel having a heat seal line. The label has an outer surface with authentication indicia appearing thereon and an inner surface adhesively secured to the package adjacent the heat seal line. The label includes peripheral portions that are frangible, with one of the frangible peripheral portions of the label being located within a portion of the area made up by the heat seal line. Accordingly, attempted removal of the label from the package will cause the label to tear, leaving at least a portion of the peripheral edge of the label secured to the package to thereby prevent reuse of the label.