There is an ongoing effort to integrate Spice into KiCad, which started probably more than 2 years ago.
But it is still not finished enough to be released in the official version.
If you install a development version (nigtly builds) of KiCad then it is probably compiled with Spice support enabled.
One of the problems with Spice though are encrypted models for components. That does not fit well with an open source project.
But it should at least be possible to export a Spice netlist from KiCad that can be used for simulation in another program.
You will also get better response from more knowledgeable people if you ask questions about KiCad on the KiCad forum:
https://forum.kicad.info/search?q=spiceMay I ask why you think that KiCad is "not for commercial purposes"?
In the "made with KiCad" section on:
http://kicad-pcb.org/made-with-kicad/You can see examples of pretty complex commercial projects such as the Olimexino boards which are designed in KiCad.
KiCad is also gaining traction with companies which only occasionaly design a PCB and this makes it hard to justify 4 digit figures or montly subsriptions for a PCB package. There is also a mighty amount of annoyance because of the cloud based folly where your own proprieatary designs are hosted on the website of some un trusted 3-rd party.
There are also no limitations to the designs you make with KiCad. You can keep the design all to yourself.
A possible exception to the library symbols in KiCad, but the consensus seems to be that there is no imitation there either:
https://forum.kicad.info/t/default-libraries-gpl-licencing-vs-proprietary-designs/140/27/ This link is more clear:
https://forum.kicad.info/t/kicad-library-licensing/7856/ However, use of the library data in your projects does not (by itself) result in the design or any files generated from your design being covered by the CC-BY-SA 4.0 License. You are free to use the library data in your own projects without the obligation to share your project files under this or any other license agreement.