confused on how to buy

hi i would like to buy one month unlimited data plan the problem is i’m confused on how to buy i dont seem to find any email/password to login to my dashboard, only thing im seeing is the extension i want to understand lets say i’m using another linkedin account, is my linkedin account linked to that subsitption, can i use subscripition on different linkedin account at the same time, can i use it on another device but with that email adress i’m confused can you please elaborate on this thanks