Things change and the User Interface is just one area, licensing/registration is another. That is going towards the aim of not having to constantly register the free version. If you didn't actually do anything, after the 30 days trial, you would still be protected and an auto-registration should take place.
Much has actually remained in the same place (in the settings) it is just a little different in getting to them.
It is very hard to imagine exactly what it is you are describing, the old or new, etc. It just so happens I was testing something yesterday relating to the free licensing. I hadn't thought anything had actually changed, however,this morning when I restarted my win10 laptop I got a popup to confirm what level of protection I wanted.
Clicking the 'Select' button bottom left of the screen (for the free version), see attached screenshot, was that the same screen that you saw ?
I later found that my registration now had 365 days remaining, so that appeared to have registered/renewed my avast free installation.