Hello,
The popup menu's should be visible untill the mouse leave the menu or you click a menu item. Perhaps you accidently do this.
However - If you click on the icon with lines left of the preset selector in the header, then you access the preset browser. That browser will stay open untill you click the x that appear instead of the lines. I suggest you try that.
About registartion/ Activation:
Registration of software can be done using Arturia Software Center (ASC). ASC is also used to updated software.
When you have bought software on Arturias website and the software appear on your Arturia account, then also install ASC. When opening ASC you just have to click a button named ACTIVATE to activate the product.
If the software is bought from another store, then you also use ASC to enter the registration code i believe. I don't think it's in popup menus, so it should stay open.
I'm not sure i've understood what you are trying to do.
Buying the software on Arturia website will be the easiest to do.
Hope this helps.