Most loyalty programme reports lead with retention rate, points issued, and members enrolled. These metrics feel meaningful because they're easy to track. They are not the right metrics.
The metric that tells you whether your loyalty programme is earning its cost is OTA share. Specifically: the percentage of bookings arriving through OTA channels vs direct channels, tracked monthly, for loyalty members vs non-members.
If your loyalty programme is working, OTA share for enrolled members should decline over time. If it isn't declining, your loyalty programme is a cost centre — you're awarding points for bookings that would have arrived regardless, via whatever channel the guest was already using.
Why OTA share is the right metric
Your loyalty programme exists to do one thing: make direct booking more attractive than OTA booking. That's the economic justification for every point you issue and every discount you offer. If it's not shifting the booking channel, it's not achieving its purpose.
Retention rate tells you whether guests are coming back. It doesn't tell you whether they're coming back direct. A guest who rebooks via Booking.com every six months is a retained guest who is still paying OTA commission on every stay.
OTA share tells you where the relationship actually lives. If it's living in the OTA channel, the loyalty programme hasn't captured it yet.