Billionaire Liu Yiqian flew to Hong Kong to pay $45 million for a 15th century Tibetan embroidered silk thangka, and he used his frequent flier miles to get there.

Liu, who used his American Express Centurion card in July to pay $36 million for an ancient Chinese ceramic known as the Chicken Cup, didn’t even know he qualified for them at the time until asked by Bloomberg.

“Since you wrote the story, I started to pay attention to the points,” said Liu, who flashed the plastic again today at Christie’s for the thangka, requiring him to sign 31 separate AmEx receipts because the system can only swipe transactions up to a maximum amount.

Liu was unclear on exactly how many points he earned today.

“I only know that I’ll collect tons of points this time, of course no fewer than the Chicken Cup,” he said.

According to the Chinese website of China Merchants Bank which issued the card, the conversion rate is one point per 20 yuan, meaning Liu should qualify for about 18,750,000 miles, including bonus awards.

Liu is using points from his previous purchase to fly his wife Wang Wei and their daughter, whose English name is Betty, to Hong Kong and back from Shanghai. He’s also flying the family to New York tomorrow on points.

Betty said on previous trips to New York her father has used points to stay at the St. Regis, though they didn’t qualify for a suite.

The embroidered 15th century silk thangka, a tapestry depicting Buddhist deities, measures 132 inches by 84 inches and was valued at HK$80 million ($10.3 million) before the auction in November, where Liu and an unidentified Western client were locked in a bidding war for more than 20 minutes.