When a SketchUp version reaches End of Support, several consequences take effect:

SketchUp 2016 License Key and Authorization Code: A Guide to Activation

Disclaimer: Attempting to use illegitimate or pirated key generators can lead to malware infections and violated licensing agreements.

If you need to move your Classic License to a new computer, you must first from one of your existing devices. The official SketchUp website provides steps to deauthorize devices in your account management portal or for older versions.

A single-user "Classic" license allows for installation on up to two devices

He had just reinstalled the OS to speed things up, but now the program was demanding its soul back.

A standard SketchUp Pro 2016 single-user license allows activation on up to (e.g., a desktop and a laptop), provided they are not used simultaneously. If you try to activate a third machine, the authorization code will return an error stating the activation limit has been exceeded. You must remove the license from an older machine before activating a new one. The Risks of Cracked Keys and Keygens