Complimentary steam?

[Elixer]

I went to https://store.steampowered.com/account/licenses/ just to check if it shows my steam keys that I have used, and I noticed, the very first item on the list says "Mar 1, 2016 Steam Complimentary"
Complimentary steam?
I didn't reinstall steam or anything... so, why is it showing that?
It also lists some titles with "Remove" next to them.

Never went to this page before, so, is this normal?

Oh, and I am still looking for a way to tell if a steam key was actually used or not, since I have a few I have, and I don't want to add them again to my account if I already own the game in question.

 

[Seba]

One possibility is that you are looking at free to play games, demos or games that were free during certain promotions.

For some games you can see the CD key in the game's page. If you have the game on Steam, that CD key is already used.