I couldn't find any info regarding how upgrade price calculation works. What does "Unused amount from previous subscription" exactly mean and how is it calculated? What happens when user switches from paid subscription to free?
First of all It is not possible to switch between paid and free subscription. Upgrade works the following way: - current subscription is cancelled. - subscription for new product activated. Discount for first payment is applied based on unused amount in current subscription. Please consider the following example. You have two payment plan: - Plan A (30$ each 30 days) - Plan B (300$ each year) User subscribe to Plan A and after 10 days made decision to upgrade to Plan B. Unused Amount = (30$/30 days) * (30 days - 10 days) = 20$ So subscription to Plan A is cancelled and user signup to following subscription Plan B (300$ - 20$ + surcharge) for first year and then 300$ yearly. Best Regards.
So in other words, the unused amount is: (subscription price)*((remaining days of subscription)/(total days of subscription)) Thanks.