If you connect it to your watch, your watch will use the H7 versus wrist heartrate monitor so it's much more accurate. It's more about where you want the information to ultimately wind up as far as which app or which device you use. At some point the H7 is just sending an HR signal, it doesn't care which app / device you use to record that signal.
I would check out some different apps or figure out what you want to use to track things and go from there. If you're using the Apple Watch, it's pretty much all built in, unless you find the Apple tracking to be lacking and want to use a third party app. I would check out the Polar Beat app or similar ones to that.