Am I allow to use any art in Unreal Engine(Such as objects that are in starter pack, and any arts that I bought from marketplace), to created my own game which I will sell it on steam, or Epic store for profit.
Read EULA as it is document grands you engine usage rights, it explains lot of things what you can and can not do, and it quite readable for normal (not lawyer ;p) person:
AS EULA States:
e. Distribution and sublicensing of Examples - You may Distribute or sublicense Examples (including as modified by you under the License) in Source Code or object code format to any third party. However, the rights in this Section 1(e) do not expand or modify your limited Distribution and sublicensing rights for Engine Code and Content (including as modified by you under the License) that are not Examples.
And on bottom you got explained what “example” is:
“Examples” means the Engine Code and Content made available by Epic in the Samples and Templates folders in the install directory or in the Content Examples projects available through the Marketplace.
And starter pack is in Samples ;]
As for marketplace you a free to use it in the game, i mean whats the point of selling it if you can not use it. The usage rights are explained in marketplace FAQ:
"There is no restriction on your Distribution of a Product made using the Licensed Technology that does not include any Engine Code "What does they mean by Engine Code? Does that mean unreal engine api?, is this mean if I want to build a game and sell it, I have to write c++ from scratch with out the use of their api?