HTC is doubling its free storage space on HTC One (M8) and HTC One Max smartphones. In addition, handsets like HTC Desire 816 and Desire 610 are also getting the additional free storage space. 
The company is offering 100 GB of free storage to aforementioned device owners. Prior tot his the these handsets had 50GB of Drive storage. Moreover, HTC is also giving 25GB of free cloud storage space on Google Drive to HTC One (M7), HTC Butterfly S, HTC One mini and HTC Desire 601.
Users will not need to update or install anything as Google will automatically add the free storage to the accounts of these smartphone owners. This Google Drive offer that came with select HTC devices needs to be redeemed by January 1, 2016, and is good for around two years. New users will have to redeem the offer from the Google Drive app on their handset.
via:Android Police