You can use the Webkul Module on only one server/domain. You can create a test instance of your production server and work with the module.
After you are done with the module work, you can transfer it to your production server. At the same time, you can use the module on your test and production server. You can also check our license policy here https://store.webkul.com/license.html.
Please do contact us for any further queries or requirements.