While there is no official version of "SketchUp Pro 2019 Classic" that is legally free, the "Classic License" refers to the legacy perpetual license
Unlike modern versions that require periodic "check-ins," the classic license was more flexible for offline workstation use. Can You Get SketchUp Pro 2019 for Free?
The short answer is SketchUp Pro is professional-grade software that requires a paid serial number and authorization code.
: Users typically paid an optional annual fee (around $120 ) to receive technical support and minor updates.