Points are a common feature of digital learning platforms, but they are typically used as symbolic feedback rather than as redeemable assets. We examine whether converting points into a functional currency improves student learning behavior, and whether the design of the redemption mechanism matters. In a randomized field experiment conducted with a large K--12 education provider in China, students in all groups earned points for learning activities, while treated students could redeem points for non-monetary digital collectible cards through one of three mechanisms: store, gacha, or time-limited redemption. Using matched difference-in-differences analysis on 7,359 student-week observations from 388 ninth-grade students, we show that point redemption increases assignment completion and error correction relative to a points-only control. The gacha design produces the strongest and most consistent effects. Mechanism analyses suggest that redemption increases motivation by giving points functional value, and that gacha outperforms deterministic designs because uncertainty prolongs pursuit of preferred rewards. The gains are concentrated among lower-performing students, female students, and non-STEM subjects. Our findings highlight point redemption as a consequential design lever in gamified education and show that the effectiveness of gamification depends not only on whether rewards exist, but also on how they are redeemed.