Can I sell a product by-product under the Apache License 2.0?

Question

I’m working on a project with Opencart (as freelancer) and need to use a certain extension, but the extension is outdated (compared to Opencart) and licensed under Apache 2.0.

So I was thinking of updating the extension to Opencart 2.0 and selling it in the Opencart Extensions store, but I don’t know if the Apache 2.0 license allows this.

I’ve been reading these two questions and their answers:

• Compatibility, legality and possible problems with the open source license change
• How Open-Source Software Licensing Works?

So I came across this phrase in the second question:

[...] think about how "free" you want your program to be: just credit it to you? Use something like the BSD or MIT licenses (or Apache, but in my opinion she is complicated beyond the necessary). [...] — Reply from @migsombr.

So wanted to know what are these complications quoted. Apache license allows you to sell a by-product derived from a product under your license?

For example, the license says the following:

You may add Your Own copyright statement to Your modifications and may provide Additional or Different License Terms and conditions for use, Reproduction, or Distribution of Your modifications, or for any such Derivative Works as a Whole, provided Your use, Reproduction, and Distribution of the Work otherwise complies with the conditions stated in this License.

That "I translated" using Google Translate:

You may add your own copyright statement to your modifications and may provide additional or different license terms and conditions for the use, reproduction or distribution of your modifications, or for any Derivative Works as a whole, since its use, reproduction and distribution of the work otherwise meets the conditions set forth in this License.

That is, it allows me to redistribute the "Derivative Work" with other license terms, but it must comply with the current license conditions. I could not assimilate well the second part with the first, because I did not understand what these conditions are.

Another material I read was the Choosealicense, where it says that the Apache License permits commercial use, and sub-licensing. That is, I can sub-license the Derivative Work and sell it?

Ultimately, the Apache 2.0 license allows or does not allow the sale of a Derivative Work?

Answer 1

Yes.

The Apache 2.0 license is a category license permissiva (within this division into categories also exist the recíprocas totais and the recíprocas parciais).

Basically, the only requirements of the Apache 2 license are the release of the license along with the code, and the indication of significant changes, not even the release of the source code.

See the details:

Image source: Choose a license

And here you can see the license in full (in English).

PS.: For the record, this trademark prohibition refers to the Apache trademark (and the trademarks of other contributors), not your trademark. Simply put, you obviously cannot use the Apache brand (or brands of other contributors) in your program, but your program can have its own brand without problems.