Steam showing weird pop up after buying some DLCs for CK2

I bought some DLCs for CK2 at Steam. Since then, Steam is showing the following pop up before launching the game.

After that, it doesn't ask me to enter the keys at all. The DLCs are showing as activated and owned both on Steam and PDX Forums. Do I need to keep these keys somewhere just in case? Found a discussion on the issue on Steam and Reddit where people seem to suggest it is a relic of the olden days and I should ignore it. Since those threads are a bit old, I am wondering if something has changed?

Solution 1:

You don't need these keys. You can safely click "Don't show me this again."

In any case, if you ever want to see this dialog again, you can go to the library page for CK2 and click the CD Key link on the right hand side:

This link also shows up in the Steam overlay.