(often written as Proteus 8/9) is a PCB design and simulation software by Labcenter Electronics.
Modern versions of Proteus (version 10 and above) have moved to subscription-based licensing, which can cost hundreds of dollars annually. Many users and small labs prefer the model offered in version 9.1. The "full upd" allows them to install the final, most stable build of the 9.x series without needing to upgrade to a subscription.