I would like to know if I have one event, with specific date, do I need to take monthly plan?

I should have about 300 inscriptions for that event. And I'll use 2 forms for that event (french and english).

Can I have a one time fee to use your service instead of the monthly fee?

Thanks for your help

We don't have this payment schedule, but you can always cancel the subscription before the renewal. When you cancel your subscription you will not be charged again, but your account will stay at the same plan until the time you have paid for expires. Example, if you will upgrade to the Bronze Monthly Plan today and then cancel it, your account will stay at the Bronze plan until January 16, 2016. 

Let us know if you have any other questions.