If you are looking to understand the features, system requirements, and the reality of finding a "free update" for this specific version, here is a comprehensive guide. Why SketchUp Pro 2018 (v18.1) is Still Popular
At least 700MB of available hard-disk space for installation. Understanding the "Free Update" Search sketchup pro 2018 v181 3d designer mac os x free upd
Ideally runs on macOS 10.11 (El Capitan), 10.12 (Sierra), or 10.13 (High Sierra). Processor: 2.1+ GHz Intel processor. RAM: 8GB minimum recommended. If you are looking to understand the features,
Note that the 3D Warehouse no longer supports direct downloads for the 2018 version format. You may need to download models as .collada (.dae) files or use a newer version of SketchUp to "save as" a 2018 file. Processor: 2
If you are a hobbyist looking for a free version, SketchUp Free (Web) is the official, safe, and modern way to use the software without a subscription. How to Optimize Your 2018 Workflow
It allowed users to embed IFC data like Price, Size, and URL directly into components, making it a viable tool for basic BIM (Building Information Modeling).