|Yes, in effect. Actually it is better than that.|
Your first 500 people are free and your first 500 signups/year are free. Thus small sites always get to use PRESTO for free. More generally, we bill quarterly for past usage. Plus a payment is required ONLY IF you want to continue using PRESTO.
Thus even large customers have no obligation for at least 3 months. And if you are dissatisfied and choose not to continue with PRESTO, you owe us nothing. The only thing we ask is that you tell us what the problem is. We really do try to respond to the needs of our customers.
To determine your approximate annual fee, just enter your expected level of usage in the little table on the Pricing page.