If you cannot afford a license yet, consider Audacity for basic editing or Tenacity (a privacy-focused fork). For a more professional DAW-like experience, Cakewalk by BandLab and Reaper (which has a very generous trial) are industry-standard options. How to Properly Activate Sound Forge
Most sites offering free serials bundle their downloads with malicious code that can steal your data or lock your files. Sound Forge Pro 12 Serial Number Free BETTER
If you need the power of Sound Forge but are on a tight budget, there are much safer and "better" ways to get the software: If you cannot afford a license yet, consider