It is quite an issue since the 7.3 version of Avada and most Avada customers do not know how to fix it. ThemeFusion changed the registration system of Avada in the 7.3 version to a new registration system. It’s based on purchase code now, which comes with the license of Avada. This registration ensures that one license is used for one website. Technically this approach makes everyone buy a license for each website where Avada is run.
Previously some people were using one token key for all of their websites, intentionally or UN-intentionally. According to the licensing terms of Envato, one license is for one website. It should be clear that licensing terms have been the same since the beginning. So previous registration system was hurting the Theme Fusion business in terms of sales.
However, implementing this new method has prevented people from using one license for all websites, and they are forced to buy additional licenses (which is the right way anyway).
Now, this issue of “The purchase code is already being used on another domain” will appear if you have already used the purchase code on another domain. But even if you did not use it, the error can appear multiple times registration was performed to the domain. The fix is quite simple and not technical. Everyone who purchased Avada can sign up for a support account in ThemeFusion. (You can register from here if you’re not registered yet) So go to your account in licenses section here -> https://my.avada.com/licenses/ and click Unlink Icon below the purchase code to unlink/reset the purchase code, and it will reset your purchase code. Once done, you can log in back to your website Avada Dashboard, and click register with the purchase code, and it will work.
That should be about it, and this action will resolve the registration issue for good.