It depends of your definition of can is. Of course you're allowed to do so. But for a desktop app with few moving parts (unlike an OS or complex enterprise soft

It depends of your definition of can is. Of course you're allowed to do so. But for a desktop app with few moving parts (unlike an OS or complex enterprise software) there's few need of support or customisation. What business models do you have left ? (Apart from being paid for education by example) ? So if you cannot financially support it long term you effectively cannot charge it. There are few exceptions and they often rely of the capability to build but I think it's a net positive since the good ideas (multiple cursors done right) can be implemented in other editors.