Why can I not upgrade Keynote???

The current version (v9.2.1) of Keynote in the Mac App Store requires the existing installation of Mojave 10.14.6, or Catalina 10.15.* before Keynote can be installed.

If you are on an earlier version of macOS, you should check your Mac model introduction timeframe in menu : About This Mac, (see red box in example screen shot), and compare that to the models under Check Compatibliity in How to upgrade to macOS Mojave.

Mojave is the last macOS that can run 32 and 64-bit applications, provided they are compatible with it.

You need to provide basic information to get anyone to help you:

• What specific model of Mac obtained from: Apple Menu > About this Mac
• What version of Mac OS?
• What version of Keynote
• What procedure did you use to try to upgrade and what happened?