Is there a way to check how long you been a yahoo memeber?

Answer 1

if you have the option selected on your public profile, then all you need to do is to view your public profile. eg, http://profiles.yahoo.com/yourID

like on mine which is http://profiles.yahoo.com/epohcj
you will see when i joined yahoo networks

I just viewed your profile and it seems the option is not selected, just click on "Edit Profile Information" and tick the "Member Since:" option at the very bottom of the page