• I think it would depend on the terms of the licensing model you purchased under.

    What version of SQL 2008 R2 did you purchase, when did you purchase it and whom did you purchase it from?

    Here's the quick guide for 2008 R2

    http://download.microsoft.com/download/2/7/0/270B6380-8B38-4268-8AD0-F480A139AB19/SQL2008R2_LicensingQuickReference-updated.pdf