is PIP valid after the end date when there has been no verbal communication after the original pip given? do they still maintain that right ,when you have actually got a review at the end of the pip period and no mention of continuance of pip?

Once a PIP end date has expired, then you are no longer subject to its terms. However, in the event that you are placed on another PIP, your overall performance will be considered as a whole, inclusive of the first PIP. If the reason why the PIP has expired without comment or extension is because you have improved, it may be worth canvassing with your manager or HR to ensure that this is put in writing.