There are two determining factors in the length of time an AWAC can sit out there collecting data for you:
Obviously the more often you ping the more memory needed to store data and the more power is consumed. Fortunately, the AWAC software is capable of estimating the requirements for both of these quantities.
If you are interested in increasing the number of days of operation (or other parameters) you simply need to increase the memory to a max of 4/16 GB or increase the number of battery packs.
Of course, if you are one of the fortunate people to have the AWAC cabled to shore then these points are of no concern.