Can you still use Quick Books online after you transfer data to Quickbooks Desktop so partner can see data on his Quickbooks Desktop?

I'm glad you ask about this, marbaent.

Let me share some information about transferring data from QuickBooks Online (QBO) to QuickBooks Desktop (QBDT).

Once you move from QBO to QBDT, you need to cancel your QBO subscription. You only have one year access to your account prior to the date of cancellation. 

Learn about what to expect when you cancel your QBO subscription through this article: What happens to my QuickBooks Online data after I cancel?

Since you're now using QBDT, you might find these articles helpful: Help articles for QuickBooks Desktop.

Please don't hesitate to click the Reply button if you have other questions about QuickBooks. I'm always here to lend a hand.

@marbaent 

You need a 3rd party solution to access your QB Desktop file over the internet.