If you previously purchased a license, you can recover it through the official developer's tools: Official FAQ & Recovery: SereneScreen FAQ page
Note: For some older versions, "TESTFISH" was used as a test, but it does not unlock the full version permanently 1.2.1 . 3. Common Key Code Issues & Fixes marine aquarium 3 key code
Access to advanced lighting, bubble, and sound effect settings. If you previously purchased a license, you can