What computer operating system are you using? Have you updated 12 to the 12.1 Update yet? If not, please do so.
Now to the question that led you to post here.
I have never found a list of Premiere Elements features that require one time activation before use. Often you might catch one for MPEG2, for MPE4, sometimes even for render the Timeline. I suspect most go unnoticed because each takes place "behind the scenes" with activation with Internet connection in place.
Can I assume that you are trying to run your Premiere Elements offline once the program has been activated at installation? Or, are you one of the users trying to bypass this component activation for a school or network set up characterized by Premiere Elements on multiple computers?
This is not Adobe. Rather user to user. And, this user runs the programs with a connection to the Internet.
One of the Adobe documents that does drop the mention of component activation is the following
And, I believe Adobe defines the situation under "Activate a component for import" in the above at the moment of need
a. connected to Internet, automatically with Internet connect
b. not connected to Internet, unlocking key