Suppose I want to licence a project I have been working on for quite some time. The goals for this license are:
- Open Source
- Free to use
- Never to be sold
What license would best suit my needs in this situation?
It's impossible, if you keep it Open Source, you can always sell it.
The Free Software Foundation says:
Actually, we encourage people who redistribute free software to charge as much as they wish or can. If a license does not permit users to make copies and sell them, it is a nonfree license.
Since free software is not a matter of price, a low price doesn't make the software free, or even closer to free. So if you are redistributing copies of free software, you might as well charge a substantial fee and make some money. Redistributing free software is a good and legitimate activity; if you do it, you might as well make a profit from it.
The Open Source Initiative says:
Can Open Source software be used for commercial purposes?
Absolutely. All Open Source software can be used for commercial purpose; the Open Source Definition guarantees this. You can even sell Open Source software.
However, there is a catch. As open source guarantees that everyone can freely redistributes it, everyone else can also redistribute the original software at no price. Or people get it directly from you. So probably selling it at an unreasonable price is not a working business model. You can make that sure by offering the software in as much channels as possible. Selling for a reasonable price though - is exactly what many commercial Linux distributions do.
This model exists as a Creative Commons license, although not as a software license, as far as I know. It's the Attribution-NonCommercial-ShareAlike-License.
You could still, as the original copyright holder, write your own license that allows redistribution under the same license, but no commercial uses. It would grant almost the same rights like an Open Source license, but it wouldn't be termed Open Source by either the FSF or the OSI.
I believe that GNU Affero GPL v3.0 might serves you well. As described bellow:
GPL is the most widely used free software license and has a strong copyleft requirement. When distributing derived works, the source code of the work must be made available under the same license. There are multiple variants of the GPL, each with different requirements.
I will not avoid the Never be sold, but forces who uses to open its source too.
For more details, pay a visit to this site from GitHub that was the source of previous quote.