To tell if your VPS hosting plan has metered or unmetered traffic, log into your HSPC control panel. Click on the Upgrade Center tab. Check to see if the "Buy Traffic" option is available.
If you have a "Buy traffic" icon, your VPS traffic is unmetered. If your VPS reaches its monthly traffic limit your VPS will become data rate limited to 8 Kbits/sec. To purchase more traffic, see the following knowledgebase article:
If you do not have a "Buy Traffic" icon, your VPS hosting plan has metered traffic and you will be billed automatically for any data transfer you use beyond your included monthly data transfer.