Every release is tested on three WHMCS versions before it reaches you

No module leaves here until it has been installed exactly as you would receive it, on three separate WHMCS instances:

• WHMCS 9.0.8 on PHP 8.3, the customer who keeps up to date.
• WHMCS 8.13.7 LTS on PHP 8.2, the customer who stays on long-term support.
• WHMCS 9.0.0, the customer who updates rarely.

On each one we check that the package installs, that its tables are created, that no file can be read from outside, and that the licence chain holds against a forged server, a replayed answer, an altered payload, a cloned database and a moved clock.

If any of that fails, the release does not ship.