Unraid is paid software (Basic, Plus, and Pro tiers). However, here is an accurate, helpful post explaining the actual free option and why you should avoid "cracked" keys.
Obtaining a completely free, legitimate Unraid key isn't straightforward due to the trial limitations and the requirement for a paid license for long-term use. However, here are a few points to consider: full free unraid key
Note: If you have a Starter or Unleashed license and choose not to pay the annual extension fee for updates, you still own the software and can continue to run the version you have indefinitely. Unraid is paid software (Basic, Plus, and Pro tiers)