The message means that a quarterly update was released over a month ago, but has not been implemented on your local server. Please do not ignore it: the FormularyComplete system administrator should follow this up with your IT department. It could be, for example, that the email addresses of the responsible personnel changed and notification of the update did not get through.
From a clinical perspective, it is important to install the BNF content updates because the available information changes over the time-span of a quarter and some drugs may have been substantially reassessed. From a software perspective, each upgrade is an extension of its predecessor, and so skipping one is not an option and no effort is saved by letting a backlog build up.