Hello @Dawood Essop !
Welcome to Microsoft QnA!
I see you want to change editions from Evaluation to PAYG
You can check here
As we can read :
The edition of SQL Server is determined by the product key, and is specified during the installation process using the installation media. The edition dictates what features are available in the SQL Server product. You can change the SQL Server edition with the installation media and either downgrade to reduce cost or upgrade to enable more features.
Once the edition of SQL Server has been changed internally to the SQL Server VM, you must then update the edition property of SQL Server in the Azure portal for billing purposes.
So i don't think you can directly do that
However you may export or backup your DBs and move them to new SQL Edition
I hope this helps!
Kindly mark the answer as Accepted and Upvote in case it helped!