A company signs up for the basic plan, but mid month they realize they need at least 6 users so they have to upgrade to the pro plan. How would I go about implementing that and how to collect the difference in payment (~$25)?
Should I update the subscription to the new plan? Or cancel the old subscription and create a new subscription? Do I calculate the difference and create a payment or does the API do it?
Hi,
It is not possible to update a subscription with a new plan. See Update subscription for all supported fields that may be updated. I suggest to cancel the old subscription and create a new one. Note that a monthly subscription can start at any day of the month. See also description of interval in Plan object.
If you set the billing field of the subscription to send_invoice when you create it, the invoice will take care of calculating the moneys due and collecting them. If you want to process it manually, you can create a payment or an invoice. See Invoice Object.