My account states it is filled and I need to upgrade but I can not figure out why?

My account state it is full and I need to upgrade but I can not seem to figure out why. I need to know to be able to choose a upgrade option that would best fit our future usage. If you could let me know why exactly this is showing up please do thank you.

Free accounts are limited to 1 payment submission per month.  The limits were changed at the beginning of the year.  Since your form has received a payment this month, that puts it at the free account limit.

Here are the limits for each subscription level:

Plan    Max Number of Payments

Starter     1

Bronze     10

Silver       100

Gold         Unlimited