Yes, and it is valid from the moment your subscription is activated. Note that we are not talking about calendar months here. For example, let’s say you activated your subscription on 14 September. Your month bundle is then valid until 14 October.
Only valid if you signed up for a subscription before 10/07/2017: every new month (at each new bundle), you'll receive 5 extra megabytes for every unused calling minute from your previous bundle. This extra mobile data will remain valid for a whole month.