IVR Manager is licensed per site, that is the total number of gateways (regional sites) you can manage.
The limit is imposed on the gateway list. When the maximum number of gateways is reached, you won't be able to add more gateways.
IVR Manager Enterprise will run for 30 days in evaluation mode. During evaluation, all the features will be available and you'll be able to configure 2 gateways.
The license can be activated by purchasing the product from Imagicle. You can enable the license in the license page as described in the Application Suite common configuration section of this guide.
To activate the license, follow the standard procedure you can find in the General configuration section.