getFormattedPricePerMonth
Recurring price of the base offer normalized to one average month, formatted in the device locale (e.g. "$5.00").
Play does not provide this string, so it is composed locally from the price micros and the offer's currency. It is an approximation for display — never present it as the amount that will be charged.
Return
Formatted per-month price, or empty string when unavailable.
Since
4.4.0
Parameters
productId
Subscription product id.