How do I offer monthly and annual billing options for the same subscription tier?

Create a single variable subscription product in WooCommerce with two variations — one for monthly billing, one for annual. Then map the parent product to your Benecaster tier once in Benecaster → Settings → Subscription → Tier Mapping.

Because Benecaster maps by parent product ID, both billing variations grant the same feed access automatically. You don’t need to create separate products or separate tier mappings for different billing intervals.