Going Back to the OP, I was caught-out by auto renewal 2 weeks early back in February. I had licensed my boat for 3 months at a time up until then. As I was funded-up in February, I intended to get an annual license, but was auto-renewed for 3 months. (I too missed the link to opt-out, or maybe just wasn't expecting it to happen 2 weeks before expiry). If I'm not funded-up for subsequent renewals, I'll have to stick with the 3 month license, which will cost me £100 more over the course of a year. So not happy.
On the subject of displaying a license, I don't always - as others have commented, most boats don't have printers. Last summer, moored on the N Oxford or Coventry (can't remember which) a CRT inspector knocked on my boat to enquire why my license wasn't displayed. Explaining as above, I offered to show him the emailed license on my laptop, which he declined as unnecessary. He did suggest a note in the license holder giving the license number. Maybe his handheld gadget couldn't get a signal?
Maybe displaying a handwritten note of the license details is not a bad idea, if just to placate irate towpath walkers (Stephen?...)