Preceden's annual plans are discounted 60% (!) vs the monthly plans, so it's an attractive option for users who need Preceden for longer projects.

I wish you had replied to my original question. I am quite curious. You must have worked out that a 60% discount, or a 66% penalty from the perspective of monthly users, is more profitable for you.

I suspect the reason is people paying annually, using it for a month, then not using it again. Or forgetting to cancel an annual plan. In short, the old school gym membership model.

Is that right or are there other factors that play into the pricing?

With Preceden, people tend to fall into two groups: those that need it for a short term project and won't use it again, and those that need it for a longer term project.

The monthly plans are there to give people who need it for a short project an affordable way to use it for a short period of time without any long term commitment.

And the annual plans are there for the people who need it long term.

Preceden sends receipts for both monthly and annual charges, and reminder emails for the annual ones. Don't get too many refund requests or chargebacks because of this.