Add Offline Device-Based Access Control to Legacy Windows PHP Application

Project Overview I use a legacy Windows application internally in my company. The application is a local web-based tool running on PHP 5.x, Apache and MariaDB. It currently runs entirely locally on Windows from a self-contained application folder and does not require an Internet connection during normal use. The application itself is already working correctly. I need to deploy it on computers belonging to several freelance contractors, but I want to retain control over the copies I distribute. Objective I am looking for a developer who can design and implement a simple additional access-control layer around the existing application. The original application should remain as untouched as reasonably possible. Ideally, I would like: - Each installation to be authorized for a specific computer/device. - Copying the complete application folder to another computer should not automatically create another working installation. - The possibility to define an expiration date for an authorized computer. - The application must continue to work completely offline during normal use. - I should be able to authorize/deauthorize computers and define expiration dates myself, without needing a developer each time. - Ideally, there should also be an administrator/master mechanism allowing me to manage these authorizations. The goal is not to modify the application's existing licensing system. I only want to add an additional access-control mechanism for copies of the application that I deploy to freelance contractors. Current Technical Environment - Windows - PHP 5.3.x - Apache - MariaDB - Local browser-based interface - Self-contained application folder - Application currently launches through a Windows ".exe" - No Internet connection should be required during normal operation Important Security Requirement The solution does not need DRM-level protection against advanced reverse engineering. The practical objective is that a contractor should not simply be able to copy the application folder to another computer and continue using or distributing it without my authorization. Deliverables 1. Proposed technical approach before implementation. 2. Implementation of the access-control mechanism. 3. Ability for me to authorize new computers and set/change expiration dates myself. 4. Testing on at least two Windows environments. 5. Short written documentation explaining: - how authorization works; - how I authorize a new computer; - how I revoke or expire an installation; - how I deploy the application to another contractor; - how to back up and recover the authorization system. Please explain in your proposal how you would approach this technically, particularly how you would provide device-specific and time-limited authorization while keeping the application usable offline.