The last chance to get any updates for Pages '09 — that was individually purchased from the OS X App Store, was when you were on Mountain Lion (10.8.5). If your Pages '09 was installed from the Apple iWork '09 DVD, then a last update (Dec. 2012) is available as the Apple iWork 9.3 updater, and puts you at Pages '09 v4.3.
The individual iWork '09 applications were discontinued, and dropped from the OS X App Store when Mavericks (10.9) was released in Oct 2013.
Never use the Apple iWork 9.3 updater with any iWork '09 applications that were individually purchased from the OS X App Store. Failing to heed this message will make your OS X App Store sourced iWork '09 applications useless.
The current Pages, Numbers, and Keynote in the OS X App Store require OS X Yosemite 10.10.4 or El Capitan for installation. Apple will likely change these requirements as future releases of these products, and macOS become available.