What were you doing when you got this message?
Is user number 10 attempting to open a file hosted by FileMaker Pro? (Maximum of 9 simultaneous users are allowed)
Do you have a volumne license and one more user than your license permits is attempting to access a hosted file?
In addition to addressing PhilModJunk's questions above, would you please post the exact message being displayed?
Thanks for sending me the message as displayed:
The maximum number licensed users are currently using this copy of FileMaker pro. Please refer to the license key section of your software documentation for further instructions. License key conflict occurred with user jane
There are messages that differ slightly and it is usually more expedient to consider the entire message to figure out what's going on.
This one, with the "License key conflict ... with user..." is most often seen when FileMaker Pro and Instant Web Publishing users are in conflict with one another.
Answer ID: 7709 describes this in detail, including a potential fix. If you are connecting to your solution with a browser, Internet Explorer or Safari, then you are connecting with Instant Web Publishing. Find out if this is the case, and ask the person who is responsible for hosting the "storefront" if anything in the configuration has changed that will affect your use of the solution.
Any additional details about the circumstances under which the message displays will help figure out its cause.