Thanks for posting in the Community, RickS,
I can provide information on how to change Payroll Service key in QuickBooks Desktop.
To start with, remove the payroll service key from the client’s subscription. Here's what you'll need to do:
Once done, you can now enter service key from your subscription. To do this task, here's how:
That's it! For additional information, you can check out this great resource: Activate QuickBooks Desktop Payroll.
As always, I'm just a post away if you have any other questions in changing payroll service key. I'm always here to help. Have a great day!