XSKey is always an option in Final Cut Pro.

Here is a bit of history,
You may or may not know this but about half of the current "Pro" software product line from Apple were companies that Apple, Inc. purchased and together with their intellectual property rights.

Logic Pro/Express/SoundTrack Pro - (originally by Emagic GmbH) bought out 2002 - Logic for windows was discontinued in 2004. I still have a PC copy that shipped OEM with M-Audio.

Color - (originally by Silicon Color, Inc) a product called FinalTouch - bought out in 2006.

Shake - (originally by Nothing Real) - IPR purchased in 2002 - Linux, IRIX and Windows support dropped in 2004 This product was discontinued by Apple, Inc in mid 2009. In 2004 no more Shake render clusters could be build with Linux, and Shake Qmaster and Smooth cam were ported over to Compressor and Motion respectively.

DVD Studio - (originally DVD Maestro and Spruce Technologies and Astare DVDDirector ) - IPR purchased 2001 from Astare and Spruce.

At least four companies holding massive IPR (not just their frontline software product) and their codebase belong to Apple, Inc.
eMagic used to protect their products with a hardware technology similar to PACE iLok, Synchrosoft eLicenser, called the XSKey. Apple's XSKey website is still operational : https://xskey.apple.com/
So now... we don't know how many of eMagic Logic Pro's components made it into Final Cut Pro 6 and 7 - however we can tell for sure the XSKey e-licenser code is one of them.

Here is my output of running the command 'strings' in Terminal against the FCP Binary

bash-3.2$ strings /Applications/Final\ Cut\ Pro.app/Contents/MacOS/Final\ Cut\ Pro  |grep XSKey
XSKey (dongle) Beta Protection Error
This application cannot continue because the XSKey (dongle) is not connected to a USB port.
You must quit this application, reconnect the XSKey (dongle) to USB port and then re-launch the application.
This application cannot continue because the connected XSKey (dongle) is no longer valid.
This application cannot continue because the connected XSKey (dongle) detected an invalid system date.
/System/Library/Extensions/EmagicXSKey.kext
The XSKey needs the driver 'EmagicXSKey.kext' in version 1.2 to be installed in the folder /System/Library/Extensions/. Please install the driver with the installer.
XSKey driver too old!
The XSKey needs the driver 'EmagicXSKey.kext' to be installed in the folder /System/Library/Extensions/. Please install the driver with the installer.
XSKey driver not installed!

My best guess for this output is that at any moment, FCP could have been or is licensed/activated via the XSKey dongle, which has become "unobtanium" after Logic 7 Pro. An assumption can be made that alpha or beta copies of final cut pro are given out with apples left-over inventory of XSKeys to qualified testers.

But fear not, Apple decided to drop prices in 2009 on all of their pro line products, incidentally leaving us the early users staring at the upgrade price tag and our old app being way more than the retail price of the new one.
Logic 7 was $1000 + $299 upgrade - A copy of Logic Studio 9 $500.

Apple, Inc also dropped the XSKey requirements from Logic Pro along with its pricetag, replacing it with the ever vastly popular Pro App A-123-ABC-123-ABC-123-ABC-123-CODE common license protection model. Which exists from Aperture to X Server.
So it's current position is not to deploy this USB dongle en-masse, but the the code for it has been kept and maintained for one or another reason. If anybody on the intarweb does know how Final Cut interacts with XSKey, please do share...

All your base are belong to us - "Apple, Inc."