Execute Cognos Reports from external web application

[Rosanero4Ever]

Hi all,

before all I'm sorry if I have chosen the incorrect forum section but I don't know what is the right section.

Anyway...I'd like integrate in a web page some Cognos analytics reports. I used the EMBED functionality which provides and <iframe> tag. This method works well but authentication is needed.
Web app users perform a login. So, how can i forward web application credentials to Cognos?
Moreover, in this way, by your experience... do i plan a consumer license for each web app user?

Many thanks in advance