since 1 year I've got a premium for family. The members of my house are six.
Now I see only 5 member with me also included.
How can I solve?
With Premium for Family, you and up to 5 members (total 6) of the same household can each enjoy their own Premium account.
It does look like your plan is full at the moment. To invite someone else, you need to remove another member from the plan first.
Hope this clears things up!