I’m using SketchUp Pro on a Mac and I randomly get told I have to log in when I open SketchUp, I’ve looked on line and it’s not the 28 days issue as I use it a couple of times a week
It’s annoying and particularly problematic when you go to use it and you’re not online
I would try and delete the login_session.dat file, it may have become desynced in some way
Frequently Asked Questions About Trimble Identity | SketchUp Help
The 28 days thing isn’t to do with how often you open SketchUp. It happens when you use an online feature having not signed out and back in again in the last 28 days.
If you are due to be offline for some time, it would be worth signing out and in again, before disconnecting from the Internet.