Users can have up to 6 cards in their account at any given time. Once you add a card it counts against your limit for a 6 month rolling period.

The rolling limit means that once you add a card to Venmo, it will count against your 6 card limit for 6 months, even if you delete it. So, a card applies to your card limit if it is (1) still on file with your account or (2) was added fewer than 6 months ago.