I have just upgraded from 5 to 7. I opened the last file I created under 5, changed it slightly and saved it as another file. Then exported to PDF. All okay so far.
Then I re-opened the original file to create a new copy. But it only opens as READ ONLY and now I can’t do anything with it.
Of course, I need to create this new file within the next few hours.
I found an old post : yes, the licence is recognised, and No, the Graffle file won’t open in TextEdit because TextEdit won’t recognise the .graffle file as openable.