An Open-To-Buy is the amount of lease limit you have remaining after executing your initial lease.
It is important to know that your Open-To-Buy Lease Limit is ONLY available to you during the time period that your initial approval is effective (90 days from the approval date). Also, the maximum number of active leases at any given time for an associated SSN/ITIN and bank account is 3.
For example: If you were approved for $2,000 of lease limit and your first lease purchase was in the amount of $500, you could add up to 2 more leases totaling $1,500 or less.