I want to activate Lightroom 5.6. The application manager keeps telling me that my serial number is invalid. This is not the case. I bought it via Amazon.de and it worked a few month ago when I still could install Lightroom without the Creative Cloud. Any solutions? Thanks!
See this thread for the info you need. You are probably trying to activate the Creative Cloud version with your Perpetual License Key.
Thank you! You were right... I stumbled upon that Creative Cloud version on the Adobe website which was very confusing. Now, with the perpetual version everything worked out!