Assuming I install TeXlive 2015 on laptop A using an online installation, is it possible to install TeXlive 2015 on another laptop say laptop B by extracting (or copying) 'something' from laptop A, copy the 'something' to flash-drive and use the copied 'something' to install TeXlive 2015 on laptop B IF direct download of TeXlive 2015 ISO file is not working. This I think will help in saving financial obligation involved twice (or for the number of fresh TeXlive 2015 installation(s)). Please accommodate my ignorance, if my question is not good. Thank you.
TeX Live installations are essentially self-contained. Assuming you go with the standard 'vanilla' installation from TUG, you will have
This entire directory can then be copied from one machine to another, and it is then only a question of pointing whatever tool(s) you use to do TeX editing to the system. At the minimum, I would add the system to the path, which will depend on the OS and is really edge-of-scope for us.