Abstract: A "return on investment" digital database usage metering, billing, and security system includes a hardware device which is plugged into a computer system bus (or into a serial or other functionally adequate connector) and a software program system resident in the hardware device. One or more databases are encrypted and stored on a non-volatile mass storage device (e.g., an optical disk). A tamper-proof decrypting device and associated controller decrypts selected portions of the stored database and measures the quantity of information which is decrypted. This measured quantity information is communicated to a remote centralized billing facility and used to charge the user a fee based on database usage. A system may include a "self-destruct" feature which disables system operation upon occurrence of a predetermined event unless the user implements an "antidote"--instructions for implementing the antidote being given to him by the database owner only if the user pays his bill.