Blender and V-Ray for Blender are free, open-source products licensed under the GNU General Public License.
To render with V-Ray in Blender you need V-Ray Standalone which is part of a V-Ray Render Node license.
V-Ray Standalone is a full-featured command-line renderer that supports V-Ray’s native .vrscene file format.
V-Ray Standalone supports V-Ray's complete feature set including CPU & GPU rendering capabilities.