To change plans, login to your account and click "Settings" on the top right of the page. From there, follow the "Manage" link next to the text displaying your current plan type. This will show the plans we offer currently and allow you to choose a monthly or prepaid rate. Our current pricing can always be found on the pricing page, as well.
Please be aware that your billing cycle is every 30 days, starting on the first day you purchase or change your plan.
Any upgraded plan change before your 30 day cycle has passed will incur a prorated charge for the new plan. That prorated amount will be the value left in your 30 day billing cycle subtracted from amount due for the upgraded plan.
You may upgrade/downgrade your membership plan as often as you'd like to.
Any downgraded plan change will ensure that credit is rolled over from the higher plan to the lower plan.