Log out of your Cloud account... Restart your computer... Log in to your paid Cloud account
Something tells me you are trying to register an old version of an Adobe product that was either registered long time ago or purchased off a pirate site? What version and products are you trying to register?
The newer Creative Cloud products don't have a registration key.
I have the same problem. A few years ago I bought Elements 9 (at Staples) registered it and was never was able to use it. When I needed to use it somehow they lost track of my registration. so that was 60 bucks down the drain. Last spring I bought Elements 11 again at Staples. Registered it, needed to use it last night, started the program and it went to the trial option. Decided to log on to the Adobe account and when I did and looked to see which products I had registered, it showed none.Again no trace of my registration. Adobe is so intent on trying to stop bootleggers, they rip off paying customers. Lost another bit of money to Adobe, again. I will be sure not to buy Adobe products again unless they make a normal software product that once installed needs no additional activation or other nonsense.
I see that you have purchased PSE13 on October 27, 2015.
I have in-boxed the serial number to that. Apart from this there are no numbers registered to your Adobe account,