Can I buy a single domain license and use it on multiple production domains in a payment system's test mode?

Sounds great Dmitry.

Initially, I will purchase 1 license of the Magento 2.0 plugin for evaluation and testing purposes.

To start of our partnership, would it be possible if we were to make the plugin available to the our merchants who’s using Omise in the testing environment and once the merchant switch to (Omise) production account (with live keys), we will purchase your license based on the activated production account?