Commerce Server 2009 is licensed in the same manner as Commerce Server 2007 SP2, meaning that Commerce Server 2009 is per-processor. As per Microsoft guidelines, per-processor licensing ignores how many cores are on a processor. For example, a dual-core processor that has two cores on it is still considered one processor for licensing purposes. Find more information about Microsoft per-processor licensing on the Multicore Processor Licensing page.
There is no price increase between Commerce Server 2007 and Commerce Server 2009. As of January 2009, the estimated retail prices for Commerce Server 2009 in the United States are:
Customers who currently have Microsoft Software Assurance as part of their Volume Licensing Agreement with Microsoft are entitled to upgrade from Commerce Server 2007 to Commerce Server 2009 at no additional cost.
