From the official FAQ :
[Apache 2.0 License] prohibits you from:
reallocate any piece of software created by Apache without proper assignment;
and
[Apache 2.0 License] requires you:
include a copy of the license in any redistribution that you can make includes Apache software;
In practice, including the "license.txt" document, which states that the software was developed with code licensed in Apache, as well as a copy of the Apache license itself, seems to be enough based on what I saw, but regardless whether these developers consulted with a lawyer before this, I can not say.
Applications in the Google Play store actually have a provision for enabling a license that users can view before downloading the application, but in practice it seems that most developers ignore this provision, possibly relying on their status as small unnoticed.
Please also note that I am not a lawyer and I am definitely not your lawyer. If you have money, it is recommended that you consult with a lawyer and not with someone at SO.
source share