Bandwidth is counted and reset on date of order/vps setup on monthly basis . For example, if the VPS is setup/resetup on 11th Jan, the bandwidth calculation will be from 11 Jan to 10th Feb midnight. Annually vpses bandwidth are also reset on monthly basis . Time zone is Los Angeles , Usa for the purpose of reset.
Both in+out (i.e upload+download) bandwidth is calculated.
Some products provide bandwidth reset.