It looks like you can:
http://h10032.www1.hp.com/ctg/Manual/c04409502 Page 84 lists up to 8GB DDR3L-12800 SODIMMs as valid spare part numbers.
You can also go to HP PartSurfer to get the official option numbers. http://partsurfer.hp.com/
PartSurfer will ask for your serial number, then show you what was installed when the laptop left the factory, and a listing of all compatible parts.
You don't have to get HP-branded memory, but do make sure the speed and timings are a match, or at least close. This will maximize your chance of a successful upgrade. I can't find info on if this has only one memory slot or two, but if it's two, get a matched pair kit.