GPL, LGPL or MPL for open source app with closed source Pro flavour

Question

I have had a fairly popular Android business app on Google Play a while now. It is available as a free version and a version with features targeted to bigger businesses.

I am currently in the process of building the next major version of the app and intend to release the source code of the free version on Github.

I have read through the licenses but feel a bit uncertain how GPL, LGPL or MPL would affect building different product flavours off of the publicly released version.

I want the freedom to have a "pro" product flavour but are a bit uncertain whether this would be considered derivative work (which, according to the GPL, would require me to release the source code for the pro version also).

I do personally not care if people would build other apps and publish them based off of the source code, but I like the idea that people have to contribute back if they change the core version, hence ASL/MIT/BSD are ruled out.

The versions that I thus feel most comfortable with right now are LGPL or MPL as they seem to cover the aforementioned cases, but as everyone knows... Assumption is the mother of all... well, you know.

Answer 1

If you wrote all the software (as opposed to incorporating other open source code), then you are not bound by the license. The license is an instrument that you issue describing how those who use that copy are allowed to use it. If you release a copy of your code with (for example) a GPL license, you still have the right to do anything you want with the original, including releasing it to others with a different license.

Some background: I have practical experience of this. When I was an employee at MIT, I wrote a nice application and wanted to put it on the FTP server (this was in the days before the WWW) with the GPL license. After a small amount of discussion and other back and forth (including the MIT lawyers emailing me a question, which I hand carried up to the FSF, and they called their lawyer to get an answer), the MIT lawyers decided that releasing a copy with the GPL did not restrict them from selling the source to another party, with a different license (essentially the standard "do whatever you want, just don't hold us responsible for the result" license that MIT uses when licensing MIT IP to others).

So, in case it's not evident: IANAL, TINLA. While I did talk to the MIT lawyers, I am not a lawyer. The discussion above is my personal interpretation of events.

Answer 2

Are you the sole author of this code? Or, if not, have the other authors transferred copyright to you? If you have the copyright, you can apply whatever license you wish, and at the same time do whatever you wish with the code.

If you do not control the copyright, then you need to reach an agreement with the other creators.

Assuming for the moment that you do have control, the question of license selection is a business question. Is your goal maximum adoption of the free version, or maximum revenue?

If your goal to get the widest possible adoption of the free version, you might consider a non-copyleft license. Some people will choose to avoid your free version if it is copylefted.

If your goal is to maximize licensing revenue, using a copyleft license will force people who can't or won't abide by the GPL to pay you for an alternative license even for the free version.

If (some of) your goals are ideological, and you simply want to use a copyleft license because that's your chosen approach, then stick to MAP's answer, which offers a more detailed explanation of the licensing question.