Registry First aids latest version is 7, but you have chance to get the version 6 genuine license.

To get this

1. Go to the promotional page here

2. Enter your email address

3. Click “Downloaden'”

4. Next page will show you the serial key with download link.

What it does

• Scan the registry for invalid or bad entries.
• Scan the hard drive(s) for the missing files.
• Select the fix for your invalid registry entries.
• Save a backup file of your registry.
• Fix the registry!

Here is a comparison chart with other Registry cleabers

[Via techno360]