Our license allows you to use a single extension license on one Magento installation.
The extension is not domain related, but installation related.
If you run several domains on the same instance of Magento, you can use one extension license.
However, if you run each website on a new installation of Magento, you need a separate license for each of them.
For more details, please visit our License page: https://bsscommerce.com/bss-commerce-license-agreement/