Good Afternoon chewbacca_hans,
The resource below will provide some troubleshooting steps if an application like Keynote is not responding. Have you used Keynote on your Mac before? Has it ever worked? Before you delete the application, back up your computer with Time Machine.
OS X El Capitan: Back up your files with Time Machine
https://support.apple.com/kb/PH21939?locale=en_US
If an app you installed unexpectedly quits, stops responding, or won’t open
https://support.apple.com/en-us/HT201398
OS X El Capitan: Install, update, and uninstall apps
https://support.apple.com/kb/PH21867?locale=en_US
Take care,