Writing fiction is a game of concentration. Here's what I mean. The book I'm writing right now, like all novels, is made up of thousands of bits of information. Scenes, gestures, emotions, moments. Two of those moments involve someone eating a small piece of rock (long story). The moments are separated by quite a long stretch of time. The main character does it the first time, in a desperate moment of hunger, and somebody else does it later in a moment of compulsion. The second moment is witnessed by the main character.
This explanation so isn't helping...
Here's my point: seed your fiction with moments that will resonate later in the story. With luck, your reader will remember when he or she sees it the second time. I hope my second scene will make a reader feel again how desperate my main character was and is. I call it a game of concentration, but such elements are really echoes through the story. Resonance. Your reader will feel smart for remembering. For finding the missing card.
One thing I'll say is not to put the matching cards too close together. I'm reading a book now that has as a title another childhood game. The author chose to build up the metaphor of the title within the story, then immediately went into a scene that involved the playing of the game. It felt too planted, to didactic. I as the reader didn't have to do any work. There was no spark between the scenes. By sitting next to each other, by touching, they had discharged all their energy.
Make your reader feel clever for finding the matching card they haven't seen since early in the game. They like to work. Promise. They love to find that chicken.