if the webhook service you use is flowboost, there is a key element in there, namely a built in counter (FBCounter) that you can use to manage the total count. This counter persists its value across time.
Cheers
Jo
Thanks for the clarification @SanfordWhiteman and @Jo_Pitts1
Thank you @Jo_Pitts1, thank you @SanfordWhiteman , really appreciate it.
I might try Flowboost based on your recommendations. I also found this service, in case anyone else reading this thread needs it: https://www.linkedin.com/pulse/marketo-tip-automatically-cap-registrations-any-form-part-mba/
The Brighthooks tool you refer to in your post is convenient in that it has a bunch of pre-built functions you can use. However:
Unless you have very high volumes of transactions calls (>100k per month), then Flowboost is free. Because you get to write your own code in there, it is wildly flexible.
Cheers
Jo