I have been using SketchUp Make (free version) and decided I wanted to try the Pro version.
I uninstalled my SketchUp Make and downloaded SketchUp Pro 2017.
Upon startup after installation the product is expired.
Please, someone correct me if I’m wrong, but as far as I know when you install the Make version it works as PRO for 30 days. If you have exceeded that time since you installed the Make version then it doesn’t matter you download the PRO version, the trial period is expired in all cases.
You’ve had the 30 days free trial of Pro from the ‘Make’ installation.
if you don’t want to upgrade to Pro (purchase a licence) you can re-download the Make installer, but will no longer have the Pro features available, as explained above.
at least on the same system.