True, people can sell software for one time purchase, for this(current) version of operating systems. Any new OS version comes, if software works, good for cust

True, people can sell software for one time purchase, for this(current) version of operating systems. Any new OS version comes, if software works, good for customer; if OS breaks things, then the developer can sell an upgrade, for that OS version. Edit: this will be difficult for server hosted apps. It will work only for apks, exe, or client sided installs.