I bought my Lightroom 5 version in 2014 and have an Original serial number. The problem is I lost my installation dvd I have a new laptop sinds a month and I tried to instal a trial version of Lightroom to change it to the complete version with my serial number. I can't figure it out how it's done... Can someone help me??
It's possible that you downloaded the CC-licensed installer. And that installation cannot be licensed with a serial number. What operating system are you using?