Since this word is made up of a single kanji, it should use the kun'yomi reading. When learning the kanji, you didn't learn that reading, so here's a mnemonic to help you with this word:
Look up at that big, bright moon. You have to open it up and take what's inside. To do that, you are required to have two keys (つき), and they have to be turned at the same time. Imagine you and a friend both turning your keys on opposite sides of the moon to open up the center.
The moon is beautiful tonight.
I also came to Japan that month.
If the pink moon comes out, that’s our signal to leave.