Your service plan cost will remain the same, unless you change your service plan. Be aware if you change your plan to something else, your old one may not be available to you anymore. The only time costs will change is from plan changes, token purchases, or other services you might add or cancel.
Though plan costs don't increase as a result of the 24 month commitment ending, if you received a 24 month plan discount when signing up your bill will end up going up to normal plan cost when that discount ends. You should be able to see any discount reflected in your invoices, which you can view in the My Bill section of the HughesNet My Account site.
You're very welcome. Happy to help.