You can still use your 2020 license perpetually if you already own it. cannot buy new serial numbers for version 2020.
If SketchUp 2020 is still installed and working on an old computer, go to Help > License > License Info (Windows) or SketchUp > License > License Info The Official License Manager: You can use the SketchUp License Manager Sketchup Pro 2020 License Key And Authorization Number
If you can't find your old license or need a newer version, SketchUp now uses a subscription model . Modern versions do use authorization codes. Instead, you simply sign in with a Trimble ID (your email address) to activate the software. Authorizing or Removing a License | SketchUp Help You can still use your 2020 license perpetually
Developing a blog post about SketchUp Pro 2020 licenses requires addressing a critical shift: Modern versions do use authorization codes
Once you have your credentials, follow these steps to activate: Open SketchUp Pro 2020. Welcome to SketchUp screen, click the Add Classic License Enter your Serial Number Authorization Code exactly as they appear in your email. Add License A classic license allows installation on up to two devices , but only one can run the software at a time. 3. The End of the "Classic" Era November 4, 2020