We develop Windows and OSX software and use anti-piracy protection on the products we offer for sale.
We informed the Media Store support team that we needed to generate registration keys via a server side php script,
and that we would supply the metrics for but not the actual script, and that this script generates keys based on the confirmed purchasers name and other parameters that are different for each product.
The support we received was excellent! We supplied a weak example of how our keygen script should work.
Turns out they know alot about emplementing key generators, They have now developed a plugin that integrates into the Media Store control panel perfectly, and does just what we requested, and addresses our security concerns as well.
These guys are the real deal folks.