How do you prove you're locked to a remote keyholder?

My keyholder is remote and asked how she can actually know I am locked when she cannot see me. Fair question. I want to give her real reassurance rather than just saying trust me, but I also do not want it to turn into a chore or feel daft.

What do people use to prove a lockup at distance? Timestamped photos, some kind of tag, check-ins at random times? Curious what actually works and feels natural, rather than like I am filing a report every day.