I just bought 2016 Sketchup pro three months ago. When I open my drawing today, it said a new version (2017 ) was available. I downloaded and open my drawing. I noticed it says that I have a 30 day trail version. I believe the agreement is that I would not be paying for any new updates within the first year? Is this part of the annual maintenance agreement? I expected not to have a trail version after the download?
Go to the Buy page at Sketchup.com and use the wizard to get the license key for SU2017 and enter it into the appropriate place in Sketchup and you will be finished with the trial period.
Ie, each version has a separate license.