A number of sets of software may be systematically distributed and maintained via a network connecting many vendors and users of client/server software. A client program in a user computer detects when software subject to maintenance is activated and transmits an inquiry over the network to the software vendor's computer for information on the current version of the software. The server program compares data in the inquiry with data relating to the latest version of the software and returns update instruction information and updated software if appropriate. The client program automatically updates the software to the latest version according to the update instruction information when it is received. The client program can also send inquires at predetermined times, or in response to a user command. The inquiry can include a request for purchase information in which case the server checks qualifications of the user, processes the inquiry according to vendor management data and returns the requested software, if appropriate. Other inquiries can also be made in response to user commands or automatically, e.g., to obtain information on the most recent version and transmission of data from client to server in response to an abnormal termination of client software.