This extension allows a shop owner to give free downloads to customers that hold a license for another product.
For example, you could make Product C and Product D free to customers that have purchased Product A or Product B. Customers simply enter their license key from Product A or B in a form and are then given immediate access to obtain Product C and D at no cost.
The license authentication form is displayed with the [edd_lfd] shortcode.
Note: this add-on requires Software Licensing to function.