How to use open source code correctly in a closed project?

Question

Licenses for software and other works

how to use open source in a closed project? perhaps someone has such information? do you need a lawyer? what to do with licenses?

Answer 1

Properly use open source according to licenses.
All information is in the license, not "someone"

Answer 2

open source licenses are different - there are more than 4 answer options in
short - until you sell - you can not bathe

Answer 3

You read license differences and that's it. And then, based on the information from the license, you decide how to use the product. Everything is simple))