When you unscrew the pen, as if you would change the ink, there is a slit that the memory card fits into. The memory card is the micro...or very tiny card, it is not the larger card. It fits into the slit. But I really did not have the expected experience with this product. Ultimately I just used it as a pen.
The pen is cheaply made and the video lacks quality. You get what you pay for and I wouldn't buy this again. I have purchased much better ultra small video devices and they are great, but they cost 100 plus dollars.