I'm not sure I understand your question, but I can tell you what I see for monthly subscriptions. When roChannelStore is queried with GetPurchases, subscription purchases return three values:
purchaseDate - the date the subscription was originally purchased; this never changes
expirationDate - the date the subscription expires; gets updated every month when it's renewed
renewalDate - the date the subscription will be automatically renewed unless canceled by the user
In general expirationDate and renewalDate have the same value. If the subscription is cancelled, renewalDate will not be present in the returned data. Once the expirationDate is passed, the entire purchase will disappear from the returned data.
This is by no means an official explanation; just my observation.
before the expirationdate if we again suscribe or if we again purchased then does the expirationDate
will automatically increase or not like for 1year subscription if we suscribed in 2019 then expire date will be 2020 but we again suscribe or purchase the product before the expire date does the expirationDate
will automatically increase or not?