Restore purchase doesn’t recognize previous purchase

I just downloaded this app again and realized the developers change this one-time purchase app to subscription-based app. Kinda pumped. But I read a review on here saying that pressing on restored purchase will grant me my app back without the subscription. So I did. But the app didn’t recognize it and said I don’t have active subscription. Urggg.

Ethanielol about Productive - Habit Tracker, v1.8