Straight from the source, Intuit spells out QuickBooks licensing. Yes, you can use a copy of QuickBooks to support your QuickBooks server company files without using a QuickBooks license.
The big take away:
QuickBooks uses both a per computer and per person license model. Last I heard, my remote accessing CPA was a person and Intuit requires him to have a license. As a ProAdvisor, I’m certain he has his own license, so I don’t have to purchase one for him. Am I wrong? Let me know in the comments.