Each DB2 database product has its own license key. Starting with DB2 Version 9.1, the license file for DB2 products is shipped separately in a file called the Activation key. This is done for convenience so that downloading the license file takes less time due to its small size.
If you purchased a DB2 V10.1, V9.8, V9.7, V9.5, or V9.1 product then you can obtain license key from Passport Advantage. The steps are completely outlined by technical article 1305417, http://www.ibm.com/support/docview.wss?uid=swg21305417