That's really interesting, it never occurred to me before (because I've never seen such thing), but it makes sense. A lot of work happens in the background, and folks don't see the value until their website is down or their certificate is about to expire.
Have you considered a trial extending to their first outage notification, rather than 14 days?
I would imagine if they don't see an outage in 14 days they're not seeing the value.
However if their trial expired following their first 'site is down' reminder - that's where your value comes in.
Just my $2c