Rearming the Expression product?

Question

Windows and Office both have methods for rearming the activation grace period.  Just curious if there is a feature or command to rearm the Expression product?  If we are using the trial and the trial period expires, would we have to uninstall and reinstall the trial if we want to continue using it? 

I understand the other option is to buy Expression.  However, I'm in the middle of a development project and there's too much red tape that needs to be crossed in time to get approval for the software. 

Thanks! 

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MCITP Windows 7 MCTS Windows Server 2008