A quick search for “license” here in the forum would have answered your question* - here you go. Well, the first part at least. Have you got a backup of /user/library/?
The imprinter data is here: /Users/yourusername/Library/Application Support/DEVONthink 3/imprinter.data - if you copy that file back from a backup whilst DT is closed, you should have your imprinter data back, I think.
Assuming I am right in saying the cause of the problem is described in the link posted above, you should be safe once you have restored things.
[* edit: well, or not as it turns out; well done, me 
]