How to Change Lync License from Evaluation to Licensed

I have followed Microsoft KB to activate Lync , http://technet.microsoft.com/en-us/library/gg521005.aspx but no luck ..Should I enter the license key somewhere ? I mean when I tried those commands in Lync management shell I had not been asked to enter the license key. I need to enter license key before it expires and I would like to keep the configuration without a complete new installation.

I have gone through Microsoft KB http://technet.microsoft.com/en-us/library/gg521005.aspx

when I enter  msiexec.exe /fvomus server.msi EVALTOFULL=1 /qb  I get following error

Solution 

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 You were trying to run the command for EVALTOFULL, but the product is still in Evaluation Version.

I would request you to run the same command (in my first email) by navigating the Lync Shell to the location “\Setup\amd64\setup” present inside the media downloaded from Volume Licensing website.