Memory used when I use Gallery icon

[Captain brick]

Im assuming that when you click on Gallery it goes to your photos in your Google account. Not assuming really since that's what happened when I went looking for a wallpaper pic. I noticed that a few pics stayed in memory when I was off line and my internal memory showed more being used.

I plan to add photos to my sd card when I install it so I won't go to Gallery much, but how do I clear this from memory?