Loyalty programs have been a staple of travel since their May 1981 introduction by American Airlines, and now the vacation rentals category is adding another: UK's HouseTrip has announced a "Collect ten nights, get one free" loyalty program.
The HouseTrip+ program is much like a traditional punchcard: for every 10 nights booked, the company offers up one on the house.
To celebrate their current and past customers, HouseTrip has offered up 3,000 free room nights as part of the program's introduction.
The program is free to join, and all HouseTrip members are automatically entered to win. The system automatically tracks bookings, and will reward customers after they collect 10 nights on the service.
As far as value is concerned, the terms stipulate that the cost of the free night will be an average of the previous ten nights booked, and the free booking must be a part of a minimum three night booking:

When you book any property and collect ten (10) nights, you will automatically get a free* night that you can use towards a subsequent booking of three (3) nights or more. The value of your free* night will be the average daily rate of your previous ten (10) nights booked. Your Free* night does not include any additional fees imposed by your Host. You can book a property that costs more than the value of your free* night and just pay the difference. Bookings made using a discount code or coupon, or including a redeemed free* night do not qualify toward collecting the ten (10) nights.
The terms are focused clearly on ensuring a balanced return on the investment for the company, while also managing a compelling offer that encourages repeat business.
There are also no blackout dates, meaning that customers can use the free night voucher for travel during peak periods, such as Christmas.
Arnaud Bertrand, co-founder and CEO of HouseTrip:

The loyalty programme is an exciting new addition to our innovative marketplace, rewarding frequent guests and making holidays in private rentals even more affordable than ever before. Internal research completed by HouseTrip has shown that holiday rentals cost up to 20% less than equivalent quality hotel rooms in all key European destinations.
For the travel hacking mileage junkies, having a loyalty program that offers a clear cut path to redemption - 1o for 1, rather than a multitude of points tiers and conditions - is intriguing. It's also easy-to-understand for those not versed in the complexities of modern day loyalty programs, adding a clear cut differntiatior for the HouseTrip brand.