Your work is a modification of a software license under Gplv3?
If yes, then you’re right. According to the official documentation:
If I use a Piece of software that has been obtained under the GNU GPL, am I allowed to Modify the original code into a new program, then Distribute and sell that new program commercially? (#Gplcommercially)
You are allowed to sell copies of the modified program commercially, but only under the Terms of the GNU GPL. Thus, for instance, you must make the source code available to the users of the program as described in the GPL, and they must be allowed to redistribute and Modify it as described in the GPL.
These Requirements are the condition for including the GPL-covered code you Received in a program of your Own.
In EN:
If I use software that has been obtained under the GNU GPL, I can modify the original code, distribute it and sell it commercially?
You can sell copies of the modified program commercially, but only under the terms of the GNU GPL. Therefore you must make the source code available to the users of the program as described in the GPL, and they must be able to redistribute and modify it as described in the GPL.
These requirements are the condition for the inclusion in a program of yours of a GPL-protected code that you have received.
Of the two software you described, only Sqlite Studio is covered by Gplv3. If you use Sqlite Studio only to develop but not to redistribute it, you do not need to follow or use the Gplv3 license in your deliverables.
The Sqlite being under public domain does not mean that you can use it for free. There are some restrictions of use, according to your license page. Fortunately for you, commercial use is not restricted.
If you deliver your software with "factory" Sqlite (i.e., how you obtained it), you will not be able to license Sqlite. Other people and companies will have the irrevocable right to create other software that they can read and write in the database that their software uses. However, if you modify the Sqlite source code to give it new functionality, you will have a derivative product, and then you can license it as well.
As for the use of Sqlite Studio, I appreciate the explanation. My intention is only to use it in the production of the application. Regarding the use of the Sqlite database I was a little confused whether or not I can license my software as copyright, because as an example, Avast uses Sqlite and I can’t find its database available for modifications.
– user100648
Nothing related to the bulk of the answer, but I saw nothing inherent in the Sqlite that prevents free use. Copyright protection, jurisprudence that does not recognize the public domain license, jurisprudence that does not recognize that the author can put the work in the public domain, tangible legal evidence that can use the product, legal department says for you to buy a license (without further explanation). All 5 reasons in my view are external to Sqlite, so
– Jefferson Quesado
@Jeffersonquesado exact, you can use commercially without problems.
– Oralista de Sistemas
@Anonreports you can include a public domain work as part of your work, as long as you don’t try to license the public domain part. I.e.: the fact that Disney makes a film telling a story of the Grimm brothers does not make it the owner of the Grimm brothers' stories - she owns only the derivative work. It’s the same with Avast and Sqlite. About not finding it for modifications, I can’t answer as I don’t use Avast.
– Oralista de Sistemas
So in my case, in a ABOUT tab I can indicate that my software has its rights reserved and that uses Sqlite as a database and only this is not licensed along with my software?
– user100648
@Anonreports I believe so. I would take care to read more about the Sqlite license, to see if it requires anything else in the "about" (i.e.: indicate date and version), but overall this is it.
– Oralista de Sistemas