Here is a super stupid question. But I really is clueless here.

I just purchased X4 (the Community of Planets Edition)
Now there is:

X4: Community of Planets Edition Key
and
X4: Foundations Key

What are the purpose of these keys ?
Where are they supposed to be used. ?

Cold it be something super unexpected. Like activating a copy on steam (that wold be like a extremely quite extraordinarily unbelievable cool)

--- edit ---
ups. the title in this post was meant to be... X4 - What are the serial keys for ?... But I can not change the spelling.

If you create (if not already have) account to Egosoft forums (in egosoft.com) you can register your game(s) using those keys.
When you have account in Egosoft then via X4 you can access to limited online features when login.
You get skins for your ships and I think Timelines leaderboard also works via online features.