The data decreases because someone or something is using it. It can even be something you're not aware is eating your data. If you have Windows, one way to see what's using data is installing the free software Glasswire.
To show that data is disappearing and have this community help you troubleshoot, you wil need to run this procedure: https://community.hughesnet.com/t5/General-Discussion/Macro-Test/m-p/117979/highlight/true#M4849
So this month I paid my bill on January 8 and it’s now January 12 and I have no data somehow. On the 8th I wasn’t able to use wifi cause of internet on HughesNet side and on the 9th I was at a relatives house and didn’t get home till that night. I called customer service and even used the text chat and they just kept saying the same thing. I only use my wifi to watch YouTube and that’s it no other devices are on the wifi. Last month was my first month using HughesNet and my data didn’t go down as much as this “month”. Do I need to reset my modem or what?
First, NO, do not reset your modem. Only ever reset the modem under the direction of a HughesNet rep, and then only in the manner in which they instruct, as resetting a HughesNet modem can not only make it harder to troubleshoot an issue, it can also cause more harm than good if not done in the proper manner, and the kind of harm that could result in the need for a tech visit. As well, high data usage is not an issue that can be "fixed" by resetting the modem.
Like maratsade intimated, is sounds very much like one or more of your devices is using your data without you being aware of it. A couple of things that can do that are satellite TV receivers, which should not be connected to HughesNet because there is no way to control it, and devices using Cloud services, whether the cloud service is proprietary or third party. As well, various streaming devices can use large amounts of data if they aren't locked down to not do so.
Though they were both primarily written before Gen5 and the WiFi capable HT2000W modem debuted, the following two threads may be of help...
Though there are Modem Isolation Test instructions in those two threads, you should follow the linked instructions in maratsade's reply if you need to run the test, as the instructions he linked to are more thorough and up to date.
Lastly, during your first twenty days of service your monthly data allotment is continually replenished. HughesNet does this as a courtesy in order to enable new customers to update or upgrade their devices to current without it affecting their normal monthly data allotment, as those activities can use a large amount of data. After those twenty days the continual refills stop and your data usage starts being deducted from the monthly allotment in the normal fashion. This would be why your monthly data lasted longer in your first month of service. The twenty days of data replenishment is mentioned in the Welcome email sent by HughesNet.
I recently had this issue. The problem started immediately after I updated my MS Surface Windows 10. Pretty much all of my allotted 20 gigs of data was consumed by the middle of the pay period. It turned out to be a mass-download of TEMP data. Check your storage settings - if your Temporary Files take up a huge amount of data (mine, for example, 700+ gigs), there's your problem.
I'm glad you found the community, thank you for posting. I hope the suggestions from the other community members helped! We're closing this thread since we never got a reply from you. If you still have concerns, please start a new thread and include a detailed explanation so we can more effectively help you.