There is no Sketchup Pro Classic licence sold currently for SU 2023.
You might have a confusion about a difference between licence (subscription) type and a product (because of the same “name” 
)
Both the SketchUp Pro subscription and the SketchUp Studio subscription allow you to use the same SketchUp Pro desktop product.
3D Modeling Software Price Comparison | Design Tools & Features List | SketchUp
