Helper app is the only way to communicate with other apps for sandboxed apps on Mac App Store, so you have to install it. But the process is really straightforward: just download helper at http://pasteapp.me/helper and dbl-click it ;)
I really like three apps:
Full Disclosure: I work at Jumpshare.
Paste is a great clipboard history manager that is easy to use and feels very native to Mac OS X. Though it does cost a few bucks. It’s on offer every now and then.
Focus has a ton of settings for blocking apps and websites for a set amount of time to let you focus on your work. $20, but well worth it for the amount of configuration and value I think.
Paste is a clipboard history manager.
You basically start by setting up a keyboard shortcut (or use the default shortcut) and you can either set up the limit of the the clips that are saved (10-50-100 or 500) or even set it to unlimited save.
All copied items/clips are organized by where they were copied from (Safari, Pocket, Pages etc.) and you can view each of them:
I love the fact that it looks like a native Mac app. The app is sold only on the Mac App Store for $4.99.