User blog comment:Katli10/i am so confused/@comment-11582536-20151225221512/@comment-32500188-20151227224413

The ActivateV4.exe is where you'll insert not just the VOCALOID4 product key, but for any additional VOCALOID libraries you have/will purchase. Just insert her product key into the field, and after you hit OK, it should bring up a dialog box with her name in it. :-)