If you aren't ready to buy a key yet, there are several free or "freemium" alternatives that can help you find chords:
Pirated versions of Chord Pickout are frequently unstable. They may crash during a transcription or fail to recognize complex chords accurately. chord pickout 3.0 registration key
A more technical, open-source tool for music analysis that can be used with various plugins to detect chords. Conclusion If you aren't ready to buy a key