Hello Anwar,
It seems that you want an upgrade license for Veritas backup exec 10.0 version.
For any License related issue you may contact our local sales team at following link,
Sales Link: http://www.veritas.com/contactus/ContactUsHome.jhtml
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You may refer the following technotes for more information on Backup exec 10.0 version,
http://support.veritas.com/docs/264482
http://seer.support.veritas.com/docs/274253.htm
http://support.veritas.com/docs/264484
http://support.veritas.com/docs/269175
http://support.veritas.com/docs/265163