The one-way door

Yesterday around 2:30 PM I learned that on Google Play, you cannot convert a "Free" app to "Paid." Ever. It's a one-way door, and I'd just walked through it without knowing.

I'd spent the past year building Meringo — a bit-perfect Android music player targeting FiiO M21 DAPs — assuming I'd ship free, then add an in-app upgrade later if traction warranted. Wrong assumption. By 6:32 PM Saturday I had two choices:

1. Ship free forever, and watch the project stall the moment I had to take contract work to pay bills.
2. Build an entire in-app purchase + paywall + trial + entitlement gating system in one day, and launch Monday.

I chose option 2.

Twenty-four hours later: version 1.24.0 uploaded to Play Console Internal Testing. $9.99 one-time, no subscription, 7-day trial. IAP flow tested end to end on real hardware. Seventy-six promo codes queued for the closed beta testers who carried me here.

Three lessons for anyone heading into similar territory

• Platform rules you don't know exist will hurt you most. Read the docs before you set your app's price, not after.
• A 24-hour sprint with a real deadline produces something. Two weeks of "planning to add monetization eventually" produces nothing.
• Solo dev is real. At 1 AM I was verifying license tester accounts in Play Console because nobody else could. Either you love that part or this isn't for you.

Meringo 1.24.0 hits Production Monday. Seven-day full trial, $9.99 if you keep it. Built for the audiophile DAP niche, works on any Android 13+ device.