Something tied to something they told you
"I know you like reading" is a guess anyone could make. "You said you finished that mystery series, so here's the next one" shows you were listening on your last call.
Something that keeps coming
A care package every few months, or a regular video call around a show you both watch. It keeps you close between visits, not just on one day.
Help with the next visit
Putting money toward a flight, a hotel or the trip itself is a great gift when someone lives far away. It's the one gift that brings you together.
Remember the little things between calls
What makes a long-distance gift personal is usually mentioned once, in passing, months before the day. Kept saves those details when you hear them, so the gift still shows you were listening.