Since AutoCAD 2014 is over a decade old, Autodesk no longer officially supports it or provides new activations for it. Instead of risking a "portable" crack, consider these options:
Using tools like Xforce Keygen carries significant security and legal risks:
I understand you're looking for a way to generate a key for AutoCAD 2014 64-bit, specifically mentioning a portable keygen and Xforce. However, I must emphasize that using or distributing software cracks or keygens can violate software licensing agreements and may be illegal in many jurisdictions.