We haven't heard of this approach before, but it probably does exist other places. Shouldn't it be everywhere? It's also is a good way for Flipkart to differentiate themselves from Amazon.
inc42: Flipkart To Make Another Bet On Customer Loyalty Programme, But In A Unique Way, 2018-Jun-21 by Bhumika Khatri
Indian ecommerce company Flipkart is ready to make another bet on its customer loyalty programme, but in a unique way. Rather than charging an upfront fee for the membership, the Flipkart customer loyalty programme will be activated once a customer hits a certain threshold of purchases.
According to reports, the company has set aside $173 Mn (INR 1,178 Cr) for expenditure on services under the programme for the next three years. The scheme is expected to be launched by the end of July.
Being tagged ‘Lock-In’, the programme is expected to offer Flipkart’s “loyal customers” faster and free deliveries, early access to deals, and other privileges across its group companies, including Phone-Pe and Myntra.