Where do I find my licenses details

Thanks ... just downloading - will keep a copy.

You really ought to keep a secure record of ALL of your software's serial numbers and license information. I put them all in a text file which is backed up to "the cloud". You should never find yourself in the situation where you don't know your serial number.

A program called Belarc Advisor can ferret out your serial number for Lightroom and other software.

Download locations given at https://community.adobe.com/t5/lightroom-classic-discussions/p-lightroom-6-14-download-is-no-longer-available-on-adobe-servers/m-p/14357593#M352977 (I don't know if this still works, but if it does, please do yourself a HUGE favor and save this installer file somewhere that you can find it again in case you ever need it in the future)

Installation requires the "offline installation" method https://community.adobe.com/t5/download-install-discussions/lightroom-6-on-a-new-pc/m-p/14638713#M580921

Or skip all of the above, and upgrade your software to Lightroom Classic, and then not only will you not have the above issues but you get tons of new useful features.