Apple often stops signing older versions of Logic when newer ones (like 10.7.3, 10.7.4, etc.) are released. If you specifically need Logic Pro 10.7.2 (perhaps for plugin compatibility) and cannot find it in the App Store, check your Purchases tab. If you downloaded it previously, it may be available in your library under "Previous Versions." Otherwise, the App Store will generally push you to the newest version available for your OS.
If you updated past 10.7.2 and want to go back: Logic Pro 10.7.2 Download
If you see a website offering a standalone "Logic Pro 10.7.2.dmg" file, be very careful. These are often malware, broken copies, or incomplete installers. Logic Pro is exclusively distributed by Apple. Apple often stops signing older versions of Logic
The base app is small, but the full sound library unlocks its potential. If you updated past 10