The demo version adds random sprite monkeys on the final image. There is no expiration and may be used as long as you like. Download link is at the top of this page.
Sprite Monkey is a sprite sheet and strip maker. Sprite sheets and strips help reduce memory for games. An image’s size is not the same as the size stored on your computer. When hard disk and memory make room for your files, they do it in clusters. Or just think of it as blocks and each block can store 4kb. To store a file, you have to have enough blocks to store it even though it’s more then what the file size is. So grouping multiple images together into a single image reduces this effect. Therefor giving better memory optimization!
Just load your png images from a folder and create your sprite sheet or strip in png format. There’s also an option to convert your 32-bit images to 8-bit or 4-bit with optional dithering.