Well your 2nd image indicates you have Activated Avast Free, what happens if you just close that window using the X top right of the window ?
Nothing and this what the Avast UI shows;

As by clicking the Continue With Upgrade, is going to take you down the paid route.
Is there not an Activate button on the bottom left of the main Avast UI window ?
Yes there is, and clicking either that or the "Extend" button, gives me this;

If not try right clicking on the avast tray icon and select Registration information, that should show if it is active or presumably give an option to activate.
That gives me this;

I'll give you three guesses what I get when I click the "Renew now" link...
If I click the little down arrow after it, it shows me an activation code (which can't be copied with the mouse), but when I type it into the activation box, it says "Cannot insert license".
Personally I feel this whole Activation, Renewal for Avast Free is a minefield in the hope that many will take the paid route.
It's a frigging pain in the ass and the fact that the Avast employees seem to MIA doesn't inspire confidence. And of course there's no option to contact them by email, at least not that I can see.
Will I even be able to register the last XP version for free if I install it from scratch?