From within the VMware web site, go to Your Account via Support.
Click on Manage Product Licencing the select Manage Product Licenses. Enter you credentials and sign in. This screen will display the licenses that you have activated and are available. If you have never retrieved the licenses that click on the NEW button and follow the instructions. If, however, you have already retrieved them, then there should be a section called My License Files. Double click on the date on which it was created and you will be able to download it again.
