before the 2022 release. Unlike older "Classic" versions, SketchUp 2022 does not use a traditional serial number or license key that you can type in. SketchUp Community

The "Classic" perpetual license—which used a serial number and authorization code—was phased out by Trimble in late 2020. Subscription Model:

If you have a (purchased before November 2020), you may still use a serial number and authorization code: SketchUp 2018 will not recognize License Number - Pro