Apple released iOS 7 Download beta links for developers. Do you want iOS 7 download and install without developer account. Done. Good news for all people. You can install iOS 7 beta without UDID.
Step 1: Download the latest official iOS for your device This will be iOS 6.1.4 for iPhone 5 and iOS 6.1.4 for all other supported devices: iPhone, iPod, iPad and Firmware/Software Download
Step 2: iOS 7 Download for your device
Step 3: Connected iPhone via USB and open up iTunes on restore hit the shift and left mouse click buttons down together this will allow you to manually search for the iOS you downloaded for iPhone 5 you would select iOS 6.1.4 for all other devices you would select iOS 6.1.3
Step 4: Once the device has restored make sure to setup as new and that you get to the home screen.
Step 5: Now on the Check for updates button hit shift and left mouse click down together this time you need to select iOS 7 for your device now when the device finishes updating it will be on iOS 7 activated.