An authorization code from a different year (like 2015 or 2017) will not work. Each annual version requires its own unique pairing.
Locating your is a common task for users maintaining "Classic" perpetual licenses in an era of subscription-based software. How to Retrieve Your 2016 License Details sketchup 2016 serial number and authorization code
Search your inbox for a message from sketchupmail@sketchup.com . This email typically contains your specific serial number and the unique authorization code required for that version. An authorization code from a different year (like
A single-user license allows installation on up to two computers, but only one instance can be used at a time. How to Authorize SketchUp Pro 2016 Single user license 2016 SketchUp pro sketchup 2016 serial number and authorization code