Software Licensing for WHMCS

Protect, sell, and manage your commercial software licenses directly from WHMCS.

Software Licensing for WHMCS transforms your WHMCS installation into a complete software licensing server. It automatically generates license keys when customers purchase your products and allows your applications to verify whether each license is valid.

Designed for software developers, WHMCS module creators, WordPress plugin developers, SaaS providers, and digital product businesses, the module combines WHMCS billing automation with secure license validation and centralized license management.

Secure License Validation

License responses can be protected using Ed25519 digital signatures, helping prevent attackers from modifying or forging valid license responses.

The private signing key remains securely stored inside your WHMCS installation, while the public verification key is added to your software and used only to verify responses.

Key Features

• License an unlimited number of software products and customers
• Automatically generate unique license keys after successful orders
• Automatically activate and bind licenses on first use
• Configure custom license-key prefixes and key lengths
• Restrict licenses by domain, IP address, installation directory, or a combination
• Support remote license checks and offline local-key validation
• Configure local-key validity and server-unavailable grace periods
• Allow customers to reissue licenses from the WHMCS client area
• Create, suspend, unsuspend, terminate, reissue, and revoke licenses
• Support one installation per license or configurable multi-seat licensing
• Track active installations for multi-seat licenses
• View license keys, domains, IP addresses, statuses, and services from one manager
• Protect the validation endpoint with configurable rate limiting
• Automatically remove old license access logs
• Provide an optional public domain-license verification page
• Use ready-to-integrate PHP validation code
• Integrate with non-PHP applications using the same validation protocol

Automatic License Provisioning

When a customer purchases and pays for a licensed product, WHMCS automatically generates a unique license key.

The customer can view the key from the WHMCS client area, while administrators can manage it from the customer’s service page or the centralized Software Licensing Manager.

On the first successful validation, the license binds to the customer’s installation and becomes active.

Flexible License Restrictions

Control exactly how each software product may be used.

You can restrict licenses using:

• Domain name
• Server IP address
• Installation directory
• Multiple restrictions together

For products that require multiple installations, you can set a maximum number of active instances per license.

Local and Remote Validation

The included integration supports both remote license checks and signed local keys.

A local key allows licensed software to continue operating temporarily without contacting the license server on every request. After the configured validity period, the software performs another remote check and refreshes the local key.

A configurable grace period can also keep licensed applications running temporarily if the WHMCS server becomes unavailable.

Complete License Management

Administrators can manage licenses using familiar WHMCS module commands:

• Create
• Suspend
• Unsuspend
• Terminate
• Reissue License
• Revoke License

The centralized license manager provides a clear overview of issued licenses, including their keys, assigned domains, IP addresses, statuses, and linked customer services.

Customer Self-Service

Enable client-side license reissues so customers can move their licensed software to a new domain or server without contacting support.

You can also configure the maximum number of reissues allowed for additional control.

Easy Integration

The module includes ready-to-use PHP validation code that handles:

• Remote license requests
• Digital-signature verification
• Domain validation
• Local-key storage
• Offline validation
• Grace-period handling
• License status responses

The same licensing protocol can also be integrated into other programming languages that support Ed25519 or compatible cryptographic libraries.

Supported License Statuses

Your software can respond to the following license states:

• Active — the license is valid
• Invalid — the key, domain, or installation does not match
• Suspended — the license has been temporarily disabled
• Expired — the license has been terminated
• Error — the license server could not be reached after the allowed grace period

System Requirements

• WHMCS 8.10 - 9.x
• PHP 8.2 / 8.3
• Requires ionCube Loader Version 14.0 or greater

Built for Software Sellers

Whether you sell WHMCS modules, PHP applications, WordPress plugins, SaaS tools, or other commercial software, Software Licensing for WHMCS gives you the tools to automate license delivery, enforce usage restrictions, and manage customers from the WHMCS platform you already use.