Hi,
I only know it like this. During install of the full version of sql which you downloaded from sap portal, there is the licence key in it.
I do not know the way where only download a key.
The key is filled in the full package and is shown during setup.
But you only should use this sql version for the Sap B1 Databases.
For each sap licence, you have to buy or sell one sql cal.