One of the biggest advantages of Photoshop Portable is its portability. You can easily carry it on a USB stick and run it on any compatible Windows machine, making it ideal for users who move between different computers.
Since no installation is required, you can avoid potential conflicts with other software on your system. This also makes it a good option for computers that are locked down by administrative policies, like public computers.
Because it's a stripped-down version of the official Photoshop, it requires far less storage space and processing power. This makes it a good option for older computers or systems with limited resources.
You can download photoshop portable online from here.