Memories are individual collectible items that you can find while you play the game. They are scattered on different levels.
Why look for all the memories?
In addition to the achievement, you unlock a secret scene. You will know who the little girl is and what a huge statue of a woman is.
Where to find all collectible items in GRIS?
The characters are scattered throughout the levels.
There are two memories here. The First you can take at the very beginning of the game. When you collect two points of light to form a bridge, then you will go left for the third. But do not go up, go all the way to the left and fall down. There will be a collection item.
The second luminous point you will find only after you complete all levels and unlock the possibility of swimming under water. When that happens, you will return to the main point (where you give away the stars), go down and to the left. Jump into the pond (you swam earlier at it) and dive into the depths to find a memory.
Second level (desert, cube form)
Go on top of the building, where a huge GRIS inscription appears. Go down and go left. There is the first memory inside the cave.
When you find yourself inside a huge stone, move to the right on stilts, climb up and jump onto the slope. Roll down and take a memory.
When you unlock the ability to turn into a cube, then you will go left from this place. Climb up, jump up and destroy the floor below you. You fall down and catch the memory.
Enter the building, where you will need to destroy the floor and fall down, do not rush to do it. Move to the right and see a small stone with legs. Move to the ledge to the right using it. Go outside and jump on the platforms up and to the right and move on top to the left. Take the memory.
When you will be in the hall with rotating platforms, you go left for the luminous point. You will see a mill. Hit the metal structure with the help of a cube. Align the construction and go to the mill. Use the blades to go up. Jump on top of the mill, and then - on the blade to the right to get on top of the structure. There is a memory.
See the screenshot below. In this place you jump in the direction of the wheel to the right direction.
You need to lower the balloon, turning into a cube. Lower the ball all the way down. Then quickly run inside the building and climb the stairs up. Jump to the top of the ball. Move left on it. Destroy the lump under yourself so that small fragments are formed. Jump on it to the left and take the memory.
Third level (forest, double jump)
You will be in the place, where some cubes disappear, while others turn into a triangle. Jump to the right and go even higher to find a memory.
This memory you can find in the same place where you will get the second luminous point on top of the tree. You need to jump on the cube to the left, go down to the cube even to the left (without a jump), and then jump to the left to remember. A cube will appear, and you can take the item.
Jump up and use red birds. Go to the right side and destroy the vase. Other birds will fly out of it. Jump up and take the memory.