• If the "Membership No." on the Contact or Account Object is blank, then it will be automatically assigned when the Payment Txn goes through the Matching Process.
  If there is already a Membership No., the it will NOT be updated.
• The "Override Target Contact Values" on the Merchant Facility must be set to Yes for the Membership No. to be assigned.
• The Membership Number assigned is from the field "Membership No.".  Membership No is based of the field "Membership Id".  If the "Membership Id" is blank then the "Membership Next No." is used.
• For accounts, the Membership No. is prefixed with "A".
• Should you wish to use your own numbering sequenced, then you could use a workflow field update to assign the Membership No. at the Contact and/Or Account levels.

NOTE: Membership No. is assigned to all contacts regardless of the payment being for a membership or not.  This is due to some organisations also using this as a support/unique contact number.  If you only require this for members, then you'll need to add your own logic with Flow etc (support on this logic is not available through standard Payments2Us Support).