Disclosed is apparatus and methodology for providing a retrofittable lock assembly for an enclosure. A manually or electronically accessible lock assembly has been provided that may be attached to an enclosure to control access to items stored in the enclosure. In a particular form, the retrofittable lock may be applied to a refrigerator used to store controlled medications. The retrofittable lock contains electronic circuitry that maintains a record of user identification, date, and time of access of users seeking access to items stored in the enclosure.