If you are running an older version (SketchUp 2021 or earlier) and have a permanent "Classic License":

When reading reviews about SketchUp Pro or discussions about obtaining a license key, look for comments on:

Sign up at the official SketchUp store or through an authorized reseller.

Once you have purchased a subscription, follow these steps to authorize your software: SketchUp plans and pricing: Compare features & subscribe

: Use your Trimble ID (the email used for purchase). The software will automatically verify your subscription status. Device Limits : A single-user subscription allows you to sign in on up to two computers