Photoshop Elements 10 not working after upgrade to Mac OS High Sierra

Hiya,

I've upgraded my Mac OS to High Sierra and have found that Photoshop Elements 10 crashes every time I attempt to save a project.  Having searched around this appears to be a common problem following the High Sierra upgrade.  My problem is that I bought the Adobe Photoshop Elements through the Apple App Store (Feb 2012) and do not seem to have a serial number or license code or whatever it is I need to upgrade the programme.  Apple have been fairly unhelpful.  Any ideas?

Many thanks,

Dave