O&O MediaRecovery needs to be licensed for each computer, in other words, you need to acquire a license for each computer where you use O&O MediaRecovery. You are not allowed to transfer this license on another computer.
If you do not enter a valid license key, you can use O&O MediaRecovery as test version. The test version allows you to search for lost files, yet it cannot restore them. Restoration is only available in the full version. Should you have any questions, please contact our Support Team.