router0 is my local isp. it provides username and password to every client for use (router1 is me. router2 and pc3 are my friends). now i want to share my internet with friends who are in same isp network. i.e router2 and PC3. They cannot access internet as they don't have is subscription, but I have subscribed.
I don't think that is possible so easily.
AFAIK , not more than one I.P. address can log in to the same user ID. Internet access is based on authentication using the credentials provided by I.S.P.
If your friends were located under the segment of your local router ( Router1 ) , it would have been possible easily.
You will need to establish NAT ( Network Address Translation ) to achieve what you are trying to do. Maybe if you are able to create VLAN then you maybe able to share the internet as well , but not sure if it's practically possible here.
On a side note , you have only one internet connection coming from ISP router->router1->PC itself, right ??