Proprietary Licence

Proprietary software is software released under a licence that you must accept, and usually pay for, before you may use it. For example, a small design studio might pay £45 per computer each year to use an image editor, and the money buys permission to use the program rather than ownership of it.

The licence sets the rules

The licence is a legal agreement, so breaking its terms can lead to legal action. It sets out limits such as how many devices or users may run the software, whether it may be copied onto a home computer, and whether it may be used in a business. A licence key is checked by the program to make the rules harder to break, but the permission itself comes from the licence. If a school pays for 25 copies of a music notation program and installs it on 40 machines, it has breached the licence even though the software still runs.

Closed source code

Proprietary software is normally closed-source. The developer keeps the source code — the human-readable instructions — and supplies users with a compiled program, which is the machine code the processor actually runs. Without the source code, changing the program is impractical, so users cannot adapt or modify the software: they cannot fix a bug, add a feature or translate the menus themselves. Instead they wait for the developer to release an update. Buying a copy gives you a licence to use the program; it does not give you the right to change its code.

Off-the-shelf

Most proprietary software is off-the-shelf: written once to be sold to thousands of customers, such as a photo editor or a word processor. Some proprietary software is custom-made for one organisation, such as a ticket system for a cinema chain, but it is still licensed restrictively and the code still stays private.