Limiting the number of paid submissions that can be made on a Form Maker form.

We use Form Maker to take paid bookings, through the PayPal link, for clinics on our website and Facebook. Only paid submissions are accepted. However, each clinic may have a different number of paid bookings allowed before the clinic becomes full. 

We are a charity/non-profit making organisation, so we don't have paid staff who can constantly monitor the website, only volunteers who only have time to look at the website infrequently. We therefore often get clinics being overbooked because there is no way of programming Form Maker to only take a specified number of paid bookings/submissions. In the submissions report to the administrator it shows whether the payment is completed, in progress, (which sadly means the payment has failed and is not in progress) or refunded, if we have sanctioned a refund through PayPal. But the programmed link is there.

Since we are a charity having to refund submitters because the clinic is oversubscribed costs us a PayPal fee which is extremely frustrating and something we wish to avoid. If there was a facility in Form Maker to state the number of required paid submissions for each form, and then the ability for the form to no longer accept submissions when that number had been reached it would be most useful. I'm sure many other users would find that facility extremely useful as well.

I know two other Word Press form plugins state they are now offering this facility. Having used Form Maker Pro since 2016, it would be disappointing to have to go to one of these other forms if Form Maker developers were not able to achieve this function rapidly for Form Maker.