You don't need a permanent internet connection to use a bought licence FlexiCloud. FlexiCloud will be locally installed and only need to be activated or deactivated through the internet. Even that is possible to do offline, with a activation file downloaded from the saicloud.com web portal.
Don't be shure about the subscription Flexi. But this should not use large traffic too as long as not using cloud functionality.
But I'm nearly shure that the minimum memory requirements are about 1GB of RAM. And it's minimum operating system requirement as far as I remember is
Windows Vista.