i have done some research and i havent found any league of legends portable now i don't know how to make a program portable but i know there are amazing developers out there so anyone interested i asked Riot Games player support to if i could get permission for making the game portable and here is there reply :
Lazy Miming (League of Legends Player Support)
Nov 17 12:30 (PST)
While we don't grant commercial rights to our content, we have a fairly thorough explanation of our stance on the use of the League of Legends IP here:
Basically, as long as your endeavor is not for-profit, we're fine with you using League as the basis for a fan project. Be sure to read the legal page carefully, though, as there are some exceptions.
Let me know if you have any other questions!
Player Support Specialist