Hello Khoa.

Thank you for your interest in our plugin.

The price listed is a lifetime license cost, with 6 months included support. So, you only need to pay once, and you'll be able to receive all upcoming updates for the plugin.

Also, please note that the following items are not free, and are available as paid add-ons:

- Powerful Filters

- Report Builder

- Gravity Forms integration for wpDataTables

- Formidable Forms integration for wpDataTables

As we are using Envato as the marketplace for selling the product, their licensing policies apply: https://codecanyon.net/licenses/terms/regular

Their policy in general is: one license is per one domain or project.

If your multiple sites are sub-sites of the same domain, and apply to the same project, you can use one license.

If these are installed on different domains, and are different projects, you would need a separate license per each.

If you have any more questions, please feel free to ask - we're here to help.

Best regards.