Hello BiBox.

Thank you for your purchase.

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.

The product will receive auto-updates after the support period expires, of course. You only need to make sure to enter your purchase code in main settings of wpDataTables:

Please note, though, that auto-update versions are usually released a week or two after the manual update.

Best regards.