Something to be aware of, is you can have this on as many machines as you need for as long as your subscription is valid, but YOU need to control your database and back it up securely. It is not stored centrally at NAPIT or elsewhere.
I do periodics as well, so I find it's good to be able to review what I've commented and coded before finalising the report.
At the moment though, I think the paper certs would be more cost effective, but the printed ones are definitely more professional.
Previously I used spreadsheet based certs, carrying a few printed blanks with me for when people wanted little jobs doing when I was on holiday!
Simon.