Thank you for posting here in the Community, @MECO.
Let me clear things out for you. You can still register QuickBooks Premier 2016. However, this is no longer a supported version of QuickBooks.
I suggest purchasing the latest version of QuickBooks. This way, you'll be supported right away if you encounter issues when managing your transactions in QuickBooks.
I've added these articles to guide you in downloading and updating your QuickBooks Desktop:
Let me know if you need further assistance. I'm here to help you. Stay safe and healthy.