PTC provides one free license of Creo Parametric for use by Windchill Visualization Services for each Windchill customer. The license should appear in the Creo license pack as "PROE_FOUNDATIONVIS". If it is not in the current license pack, then most likely the free line item was left off the Windchill sales order. This is a very common mistake because sales reps don't get paid for free line items and they don't realize this package is necessary.
Contact your PTC sales representative and ask them to submit a zero-dollar sales order for the following package. Once the order is processed, you can download the license and use it with visualization publishing.
PKG-5055-F Windchill Visualization Adapter Starter Package “No Charge”