In many countries, circumventing DRM or using unauthorized license keys violates copyright law. While individual prosecutions are rare, ISPs and rights holders can issue warnings or take legal action in severe cases.
Any site claiming to sell a "Tekken 6 PC license key" or a "full PC setup" is likely providing illegitimate files or malware. To play Tekken 6 on a PC, you must use emulation. Official Ways to Play (Legally) tekken 6 license key for pc game