Most "free" keygen tools are bundled with malware. By running these on your management workstation or attempting to "patch" your router, you may be installing a backdoor that allows hackers to intercept your network traffic.
Every RouterBOARD device (like the hAP, cAP, or RB series) comes with a pre-installed, permanent license included in the price of the hardware. Conclusion
Official Level 4 licenses (the standard for most small-to-medium setups) are relatively inexpensive and provide a lifetime of free updates.