EDD Software Licensing is really intended to help developers license the use of WordPress plugins. The EDD SL API can be used to provide some licensing capability to desktop products but in a limited way. The existing API is able to restrict the use of a licensed WordPress plugin because the licensing code you host on your web server can inspect the site on which the plugin is being used which WordPress passes automatically in the user-agent header.

When the API is used from an application running on, say, the Windows desktop there is no natural equivalent of ‘site’. Without a site, or some equivalent, there is no way to restrict the use of the licensed software. The license can be used once or any number of times. However once licensed, what’s to stop the software and license being copied to another device?

So it will be helpful to have a unique value from the client environment to associate with the license but one the client is unable to change. The user’s IP address cannot be used because the address is probably allocated dynamically. Although the user cannot change the address, it could be changed any time so when the desktop application tries to validate the user’s license. Another potential value is the CPU id. Here the problem is that the user’s PC may be upgraded changing the CPU.

However, a value that can be used, which is guaranteed not to change, survives PC upgrades and which is unique to each user’s session is the Windows Security Id. To end users, Windows security, it’s access and control is accomplished through the use of a user account name and associated authentication token such as a password. To Windows an account name is just a human readable proxy for a security Id. In fact a user maybe interacting with up to three security ids: machine, domain and account.

This plugin extends EDD Software licensing to provide more robust support for Windows client software by using the Windows user’s security id to identify a license and, if appropriate, restrict the number of activations per license.

Restricting the use of software to a specific security id is, well, restricting. What if a user wants to be able to disable use of client software on one PC and enable use on another. For example, disable use on a machine at work so it can be used at home.

The plugin includes the ability for a user to change the active security id. The user interface to this functionality is available through a page added by the plugin that you can add to your ‘My account’ menu or other suitable entry point.

The plugin supports a greater range of licensing types. You may want to use periodic subscriptions but you may also want to provide perpetual licenses or trials. You may want to allow enterprise clients time to settle their invoice for a perpetual license purchase but still be able to use your software. You may want to be able to offer an unlimited number of licenses or in blocks of 5, 10, 15, etc.. These are features.

The plugin is installed the same way as any 3rd party plugin: download the plugin zip from your account after purchase; use the WordPress plugin manager to upload and install the plugin.

However after installing and activating the plugin, visit the ‘Extensions’ page of the EDD settings, locate ‘Security Ids’ and enter the license key that will have been included in your invoice and purchase notification email.

Easy Digital Downloads core and the EDD Software Licensing plugins must be installed.