Latest version is 2.29. And not working with serial key
Yes, eMagicOne did some changes in version 2.20 or 2.21 don't know witch the latest build this key would work with. Just have to install and see what happens.
I have seen a very nice solution to this on Store Manager for Magento, where a fake license server is set up with php that always gives a correct answer to the
Store Manager client.