Gargoyle Forum

can i use gargoyle to set daily data limits on all individual devices through the router to ensure no over limit charges at month end.

yes, per device

ensure no over limit charges at month end

for various reasons the gargoyle counter and your ISP's counter will not the exact, but it is very close.

keep this in mind when creating device limits

Yes definitely using quotas. You might be interested to read some common scenarios:
http://www.gargoyle-router.com/wiki/dok ... _scenarios