Set Data Plan on unlocked Netgear Unite Explore AC815S

Hi Jason_N, my question is...on an unlocked AC815S, and while I'm using the device on a pay-as-you-go cell network here in our African country (we work in Gabon), how do I enter the info for the data amount that I've purchased and the expiration date for that data amount? How do I enter these numbers/dates into the AC815S so that it will then be displayed on the touchscreen of the device, like it is often shown in the promotional pictures of the device?  I have looked on the web-browser interface page for the device, but I haven't found the option/screen there, and I've also tried using the touchscreen options on the device itself, but no success there either.  So, if the touchscreen can display that info (which all of the online images of the device show that), then how do I enter that info into the AC815S so that it shows up on the web-browser interface page, as well as on the touchscreen display of the device itself?  Having this info at-hand like that would be VERY helpful in keeping up with how much data is left before I have to buy more and keep my internet access working. Thanks for your help...