What do you mean with "KMEM is not 64 bits" ? A scenery doesn't have any "bits", it's just...a scenery.
Only a software can be either 32 bit or 64 bit, and the support software required by KMEM to work ( the Couatl scripting engine and GSX ) are all available in 32 bit and 64 bit with specific versions for FSX, P3D4 and P3D5.
If you wanted to know if a KMEM license can be used in all supported simulators without paying extra, then yes, all our products for FSX, P3D1/2/3/4/5 can be used with a single license.