Nike app won't download to phone just opens from App Store??

Nataliehun wrote:

but it only has the option to open it via the App Store

Well, that means that it is, in fact, installed on your phone...just not visible. Try resetting your phone:

Press the Sleep/Wake button & Home button at the same time, keep pressing until you see the Apple logo, then release.

It might still be installed, but a bug might be causing it not to appear. Try these:

• Do a Spotlight search. On the home screen, swipe down from any icon to bring down the Spotlight search bar. Search for Nike - it might show up.
• Do a soft reset. Hold the sleep/wake and home buttons for about 10 - 15 seconds or until the phone turns off and the Apple logo appears, at which point let go of the buttons. Unlock your iPhone and look for the app.
• Reset your home screen layout (this will delete any folders and place all of your apps on the home screen). Open Settings, then go to General - Reset - Reset Home Screen Layout. After the process completes try looking for the app.

Hope this all helps!