that depends of what engine you want to use for example cryengine2, i doubt you can use them, you need to convert them using some specific program for that engine
WTF is this? Uhhhh.... Why would this guy try and sell this? And the asset use, and method.. This must be some situation fueled by serious autism with comorbid mental illnesses of a foreign kind that we can not understand without the proper education and assimilation in to the man's culture..
for example cryengine2, i doubt you can use them, you need to convert them using some specific program for that engine