well yeah, old classic licences were linked to a motherboard. so if you change your computer, you’ll need to re-activate sketchup on it using your serial number and authorisation code.
if you’re out of activations, @colin can check if by any chances you have a 2020 available
Removing the license from the old computer will free up one of your activations, which will become important if you want to put SketchUp 2019 onto yet another new computer.
For now, I will send a message with your license details.