If you have subscription each version of SketchUp where you are logged in counts as a ‘Device’ so the count on one machine even may be more than you think.
Manage the devices on myaccount.trimble.com (log in with the email address that uses SketchUp)
On the left, choose ‘My Products’ than hit ‘View included Apps’ and under SketchUp Pro, use the ‘Manage Devices’ link to deauthorize all.
This will reset the count.
Restart SketchUp and log in if necessary.
Btw. each team member needs to do this for themselves, you cannot do this for them being an admin, in case they’re running into this problem.