How can I copy and paste from one screen onto an app and save it for later reference?

I have an iPad Air and iPad Air 2. Would like to be able to copy text from one screen and then paste it in an app that would let me paste and then give me a way to save it or keep it on the app for later reference.
I'd prefer a free app if one exists.

db

If you're syncing Notes... you can do what you're wanting to do. A Note created one place will be available on all devices...

Use the notes app already on the iPad and sync it via iCloud.