If you still have LR5 installed, you can retrieve the serial number from a file called Lightroom 5.0 Registration.lrreg
Open the file in a text editor like Notepad, and you'll find the serial.
On Windows, you'll find this file in C:\ProgramData\Adobe\Lightroom
Did you actually purchase LR 5? If so did you register it with Adobe.com? If so then login to Adobe.com with the AdobeID you used to register it, click Manage Account then into the Products area a couple clicks and you should see the serial number for LR 5 that you registered.
If you never had LR 5 then maybe you can return what you bought and purchase the correct license. Try here:
Thanks for that,
just to to note it is a Mac version, searched the library but still could not find.
a Friend installed it couple of years ago, so don't have disk, box etc.
not looking good....
If you didn't buy LR5, but "got it from a friend", you are not entitled to an upgrade.
Follow ssprengel's advice above.
That is all I am trying to do here guys, found the licences key info for L5, but number is not revealed, as in private?
Can't seem to return or replace unless changing platform.
I don't wish to change platform, just need to exchange for full version, option not available, I will contact support and explain the whole situation, hopefully just let me pay the balance and get sorted.
New to this, lesson learned, always buy and don't let FRIEND install unless providing key!!