Registering "invited" Ultimate computers

Hello folks,
After installing/purchasing the TuneUpPro package with great results on a problematic Asus desktop, I decided to contact (via online chat) AVG. In a nutshell, "Clairine" offered to issue a refund on my TuneUp single license, and sold (at my request) me an Ultimate package.  The understanding was (and yes, I saved the chat) I can invite other machines at our location to join my Zen(?) and make use of a suite of AVG tools, including TuneUp.
After registering the license key on the original machine, I am finding it completely impossible to do the same with our other (3) machines.  I see no menu listing for entering the license anywhere.   I log into the account, and it dead ends. On the second machine with the  installation, by invitation, I'm told I've got several days left.
WHAT is the trick to entering the license.  It rejects other emails, and when I attempt using the same email (my MS outlook address)  I am repeatedly told that address is already registered.
I'm quickly losing patience with the whole thing, and thinking of asking for a refund.
If that's not enough,  I have yet to see the offered refund on the singular TuneUp pro license.

Please help!  This all seems pretty underhanded to me.   Disgusted.