If we have a public website that allows users to sign up for a "My Account" type account, and we want a central location for all authentication (which would include employees and dealers as well), is AD a good fit?

My only question is licensing.....will each "My Account" account need a license?  Im assuming it does.........so my last question would be, how does everyone handle situations like this for their sites?  Custom authentication modules?  If so, any examples?

Thanks in advance.
-Chris

All of our userbase currently exist in an SQL table and we use custom authentication to let them into our "MyAccount" subsite.  While we can import the users directly into DNN without a problem, our goal was one central location for auth, including for employees and dealers, along with the existing "MyAccount" accounts.

Since some of our users and dealers are in LDAP, some are in AD and some are in the SQL db, I was hoping there was a common auth scheme that DNN could reach out to, while avoiding keeping all users in DNN, LDAP, AD, etc.  ADLDS seemed to be a possiblity, as it can synch with different sources, but ADLDS doesnt seem built into DNN yet, just straight AD.