I have several lenovo e440 whose sketchup says they are not on the internet to put in the serial number and passcode. Even though I can surf the internet with Chrome. Help
Older versions of SketchUp checked google.com to see if you are online. If you are in a location that blocks google.com that might fail. Unfortunately, in 2018 that URL doesn’t have a setting. Perhaps you can do VPN to appear to be in another location.
You say that you are using SketchUp 2017, 2018, and 2019. If those are with the same license you mosts likely would not be able to add a 2018 license anyway.