Block Breaker Deluxe 2 - How does the shop work?

I just got this game for my iPhone, but I gather that it’s been around on other platforms for a while, so I’m assuming there will be no shortage of people who can answer a newbie’s stupid question:

How does the shop work? I played for a while, earned enough money and stars to buy some stuff, so I bought the Satellite ball, the Shield, and the Add-on Stack. I went back to the game and . . . Where’s my Satellite ball? Where’s my Shield? Back to the shop, it’s got the little “x” in the first box on those items, so it remembers that I bought them.

So, where are my items? Is there something I need to do to activate them?

Looks like a duplicate thread. Let’s direct responses over to the other one