Yes, you can upgrade your perpetual license. If you have a perpetual license of V-Ray 5, V-Ray Next, or V-Ray 3, you can upgrade to a perpetual license of V-Ray 6 (currently available for 3ds Max, Maya, SketchUp, Rhino, Revit and Cinema 4D.
You can also migrate to the new subscription annual plans with a discount for your first year and keep your perpetual license.
Upgrades can be purchased through your local reseller or through your Chaos account. For more details see our upgrade options.