Hi Bear.
When you take a screen shot while in the game using the C key or the camera icon found on the user interface, the images go into the Screenshots folder of the game. On a PC, it's located here: C:/Documents/Electronic Arts/Sims 3/Screenshots. I haven't messed with memories (I ignore all of them), but I didn't think that these screen shots would go there. Pressing the C key should always put them in the same spot that I mentioned.