The old Shareware model isn't too different than this. If the user opts not to pay, they basically have something close to what you describe. There are also a

The old Shareware model isn't too different than this. If the user opts not to pay, they basically have something close to what you describe. There are also a lot of free apps for tablets and smart phones. Some are open source, but definitely not all of them. But I think a lot of people do (rightfully) look a gift horse in the mouth. If it is free, the lack of source code availability calls into question 1) Why? Is there something that needs to be hidden in there? and 2) what to do if the software suddenly is no longer supported by the author, be it through disinterest or death or whatever.