No - membership allowances (mobile call minutes, texts, landline call minutes and data) last until used up or until the membership expires at the end of the membership month - whichever comes first.
There is no carry over of membership allowances from one membership to another.
And add-ons last until used up or until the end of the following membership - whichever comes first.
Cash credit is not lost at the end of the membership month though!
Hope this helps.
Did that help at all?