We are a new start-up team based in Europe and have few or none knowledge on usage of patents and patented technology. We designed a chemical process that includes buying and using a patented technology (US patent) for ONLY a part of the entire process. We have doubts concerning the legacy of using this technology. If we buy the technology from the producer that possess the patent, do we also have to buy a license for the patent? The producer has a company specifically selling the technology we need.