You do not need to purchase or find a "new" registration key to use the full features of the software for development or testing.
Because no registration is required, you can immediately access the following professional-grade simulation features:
To ensure you have the most secure and feature-rich version without worrying about registration prompts, download from official repositories: modrssim/src/mod_RSsim/About.cpp at master - GitHub
Supports scripting for automated simulation of PLC program actions or I/O states. How to Get the Latest Version
Includes a diagnostics screen that shows real-time traffic for Modbus commands and responses.