I previously downloaded a trial version of lightroom 5.6 and decided to purchase it outright. I paid for the product and was emailed a product registration key which I have tried to enter several times and on each attempt I receive a message that the product key is invalid. Please help!
You are probably using the Lightroom Creative Cloud trial version. The Perpetual License key will not activate it. Uninstall Lightroom, this process will not interfere with your Catalog , preferences or personal files. Download Lightroom from the link below and run the install, insert the License key and all will be fine.