Access via Weblink will default read access (always), independent of the type of license the user to authenticate.
You'll note that the user with a full license can simultaneously authenticate the client Laserfiche (WebAccess) and WebLink without any problem.

Excuse my English, but my native language is Castilian.

Before with version 8 it would default to the read-only first with the option to use the Full license if one was available.  Now my understanding is that WebLink will use the full-license only if profile isn't set to read-only.  If we set the account to read-only then they won't be able to use the WebAccess?  What about customers that purchased read-only licenses for the sole purpose of using them for WebLink, ten years ago?  They are using Windows Authentication and do not login to Laserfiche.  Is my only option to have the customer to login manually to a duplicate (twice the licenses) account to be able to use the WebLink as a read only?  Or can I use one account and set it as a read only, and have 30 different users log into that one account account at the same time?

If they do not otherwise require read-write access into Laserfiche, you can just set their accounts to 'read-only' in the Administration Console and they will use read-only licenses when they log in. 

They curently need to access both the WebLink anf the WebAccess.  If they are just viewing a document they have been using the WebLink to do that.  If they want to scan or add documents they use the WebAccess.  They must have access to both like they had in the past versions of Laserfiche.  I just need the WebLink to pull licenses from the Read-Only pool if possible.  Can you please tell me what my options are?  Can I use the WebLink version 8 with Laserfiche 9? Can I then pull from the read-only licenses like before?  The customer doesn't want to have to change proceedures to accomplish this. 

This behavior has been present since the v8.0 Server and is independent of the version of WebLink. A user must be flagged as read-only in order to use read-only licenses when logging in as that user, that's basically all it comes down. That only applies to direct user login though - you can certainly use auto-login as a predefined user through WebLink if that predefined user is set as read-only. Of course, then everyone will log in as that user. 

Will I be able to use the predefined user and log in with 30 individuals using it at the same time on different PC's?

Each user license has a session limit of 4 I believe.

The Weblink public portal is intended for the scenario of having multiple individuals logging in through WebLink as a predefined public user. That is not an intended use of named user licenses, regardless of session limits.