what is Volume License Key (VLK)?

Volume License key (VLK) is a term used by some computer software companies to denote the product key used when installing software licensed under volume licensing, which allows a single product key to be used for multiple installations. This form of licensing is typically used in business, government, and educational institutions, with prices for volume licensing varying depending on the type, quantity and applicable subscription term. For example, Microsoft software available through volume licensing programs includes Windows Vista, Windows Server 2008, Microsoft Office 2007 and many others.

Volume Activation 2.0

Starting with Windows Vista, VLKs have been replaced with Multiple Activation Keys (MAK) or Key Management Server (KMS) keys. MAK Activation may occur independently (by means of connection to Microsoft through internet or telephone activation) or through a proxy using Microsoft's Volume Activation Tool (VAMT). Hosts activated via a KMS have to report back to that key server once every 180 days.