Your license information would have been emailed to you, when you made your purchase.
If you can't find the email, you can use
https://voiceattack.com/lostkey to have the information re-sent.
For your commands, assuming you still have access to the old hard drive, the profile database is normally stored under "C:\Users\<your Windows user account>\AppData\Roaming\VoiceAttack" (note that the "AppData" folder will likely be hidden by default; you may also need to take ownership of the files)
If you copy the VoiceAttack.dat file to the corresponding location on your new drive while VoiceAttack isn't running, overwriting the existing file if necessary (do make sure you're overwriting new with old and not vice-versa; consider making a backup copy first), your commands should be available when you start VoiceAttack.
Obviously any commands/profiles in the new database you overwrite would be lost. If you want to keep those, export them first, so you can import them into the old database.