Only paying customers get a valid key.

specifically for a WordPress plugin.

Locking a license to a specific website domain. Usage Tracking: Seeing which users are using the software. Best Practices for PHP License Management

: Many systems use OpenSSL to generate a private key (to sign the license) and a public key (embedded in the client app to verify it). Activation

use Dev3bdulrahman\LicenseManager\LicenseChecker;

While Laravel Spark is a paid product, it provides a comprehensive SaaS-style licensing and subscription management framework built on top of Laravel. How to Build a Basic PHP License System