Searching for "activation keys" or "cracks" for software like Recover My Files v6.4.2 is a common reaction when you're trying to get important data back, but it usually leads to more trouble than it's worth.

If the computer has no internet, select Activate Offline Manually in the activation window.

Recover My Files v6 is professional-grade software. While you can download a trial to preview files for free, a license is required to save them:

Finding a Verified Activation Key

Verdict: If you have a key for v6.42, it is legitimate and the software works effectively. Just remember to disconnect from the internet during activation to avoid error messages. It saved my data, so it gets a recommendation from me.