You wish to ship your software as a zero-cost binary ("freeware") whilst reserving source code to paying licensees, who will not be permitted to use it to make products for general distribution. You want to know if you can release the binary under an MIT licence without causing yourself problems.
Interestingly, this is the second question we've had here recently about using the MIT licence on a piece of proprietary-source freeware. The more I think about it, the more I think it's a reasonable idea. Using a well-established non-copyleft licence for your binary makes it immediately clear what is permitted with the binary (including using it, copying it, selling it, and reverse-engineering it). However, it is in my experience an unusual way to use this licence, and IANAL/IANYL, so you should take professional legal advice before betting the farm on this.
You may also wish to consider using the Apache2 licence for your binary, instead of MIT, as the patent grant therein will further reassure potential users that they're not exposing themselves to any liability by adopting your binary.