How can I use more payment submissions for 1 month only?

We only receive payments twice per year for our not-for-profit church ministry, which means we only need an upgraded plan for 2 out of 12 months of the year. 

Is there a way to only upgrade for the 2 months that we need space for more payment submissions?

Hi,

You can simply downgrade back to "Free" plan before the next billing date. Here's how: https://www.jotform.com/help/341-How-to-Downgrade-Subscription-Back-to-Free-Account 

For example, you want to have a Bronze plan from December 28, 2016 - January 28, 2017. You then upgraded this December 28, 2016. Anytime before January 28, 2017, you can downgrade to "Free" plan, that will automatically set a scheduled downgrade to your account, your account will then be downgraded to "Free" plan the next billing date, which is January 28, 2017 in this case. You will not be billed anymore further then, if you wish to be in a paid subscription again, then simply upgrade. 

You also mentioned that you are a non-profit organization, we have a special pricing for non-profits, you can check this link for that: https://www.jotform.com/nonprofit/pricing/. You'll need to first send your application using that link and wait for an approval. 

I hope that helps.