Unlike modern versions (8.x and 9.x) which require heavy .NET frameworks and constant online activations, version 7.8 was relatively lean. This makes it an ideal candidate for portabilization.
While newer versions of Proteus offer more features, they also require more modern OS specifications. Portable 7.8 is frequently used as a "fallback" tool because of its proven stability and its ability to run on a wide range of Windows environments via compatibility modes. Historical Significance and Limitations portable proteus 7.8
Comparing FPC Design Features in Proteus and Leading EDA Tools Unlike modern versions (8
Proteus Tutorial How to Add Text to a Schematic portable proteus 7.8