Usually, it means a keygen (key generator) or a patched libMAMP library file has been tested and doesn't immediately crash the software. However, it rarely means the key works for more than 24 hours or across updates.
If you have purchased a license, you must enter it into the software to unlock professional features. Open MAMP PRO 7 : Launch the application on your Mac or PC. Access the Registration Menu : Navigate to the menu at the top of your screen and select mamp pro 7 license key verified