Can I pay for my add-on with a different card?

No. Benecaster stores one payment method per account, and it applies to everything — your plan and all add-ons. You can update your card from your account, and the new card is used for all future charges on all subscriptions.

This is intentional: one card on file means one place to update, and no situation where a plan renewal succeeds while an add-on renewal fails on an unrelated card.