Projectopia provides an admin dashboard that shows all subscriptions as well as those that are due within 30 days, and those that are overdue (had a failed payment), along with the status of each subscription and when they are due to be billed again.
To manage an individual subscription, click the title of the one that you want to manage and you will be taken to the subscription management page.
On this page you can access information such as when the subscription was activated, when it last billed, how much was billed and when billing is due to occur again.
You can also use the line items metabox to edit or add to what is to be billed in the subscription going forward.
If you have invoices activated for the subscription, then these will be shown in the invoices metabox for easy access.