If you legally purchased software like Proteus VSM, Labcenter Electronics, or Eagle + sim, then:

Instead of looking for a license key for outdated software, I strongly recommend using one of these free, industry-standard simulators:

1. Wokwi (Web-Based - Best Overall)

2. Tinkercad Circuits (Web-Based - Best for Beginners)

3. Proteus (Desktop - Advanced)

However, I need to clarify a few points:

Given your interest in an Arduino Uno simulator version 1.8 and a license key update, here are some steps you can take: