Subscription for sales invoice

Hello everyone,
I want to know how subscription works?
I am using it, but I am not sure if it works as scheduler.

Have you checked this: https://erpnext.com/docs/user/manual/en/accounts/subscription

Thanks for replying @lasalesi,
Yes I already checked that, but whenever I am fetching subscription updates , new invoices are generating.
It should be like that, one invoice per day, if interval = day is selected.
I am still confused.