Can I change my pricing plan as needed?

My organization accepts more payments and submissions during a 2 to 3 month period each year so we would need an upgraded plan during this time but the rest of the time the free pricing plan would be adequate.

Can I upgrade during this 2 to 3 month period and then switch back to the free plan after that?

Yes, you can. You can upgrade today and cancel it before the auto renewal will take place. 

Thanks