Photoshop CS3 was originally designed for Windows XP and Windows Vista. While it is a 32-bit application, it can generally run on 64-bit systems like Windows 8.1 64-bit. Will cs3 work in windows 8? - Adobe Community
Adobe officially for Photoshop CS3 years ago. Crucially, the activation servers for CS3 have been permanently shut down. This means even if you have an original installation disc and serial number, the software will often fail to activate and may stop working after a 30-day trial period. There is currently no official way to reactivate this legacy software through Adobe. System Compatibility with Windows 8.1 adobe photoshop cs3 download for windows 8.1 64 bit
Adobe Photoshop CS3 is an iconic, "classic" version of the world’s most popular photo editor, known for its speed and lightweight footprint compared to modern Creative Cloud versions. While it is older software, many users still seek to install it on Windows 8.1 64-bit to maintain access to familiar workflows without a subscription. Photoshop CS3 was originally designed for Windows XP