How to get the Account products including the 'Support Expiry Date' with the CRM API?

How to get the Account products including the 'Support Expiry Date' with the CRM API?

The account products can be obtained using:

Products/getRelatedRecords?newFormat=1&parentModule=Accounts&id=<AccountID>

But the result does not include the 'Support Expiry Date' field.

<?xml version="1.0" encoding="UTF-8"?>

<response uri="/crm/private/xml/Products/getRelatedRecords">

<result>

<Products>

<row no="1">

<FL val="PRODUCTID">831527000000061031</FL>

<FL val="SMOWNERID">831527000000061001</FL>

<FL val="Product Owner"><![CDATA[eharrington]]></FL>

<FL val="Product Name"><![CDATA[Product1]]></FL>

<FL val="Product Active"><![CDATA[true]]></FL>

<FL val="SMCREATORID">831527000000061001</FL>

<FL val="Created By"><![CDATA[eharrington]]></FL>

<FL val="MODIFIEDBY">831527000000061001</FL>

<FL val="Modified By"><![CDATA[eharrington]]></FL>

<FL val="Created Time"><![CDATA[2013-04-03 13:09:03]]></FL>

<FL val="Modified Time"><![CDATA[2013-04-03 13:09:03]]></FL>

<FL val="Unit Price"><![CDATA[0]]></FL>

<FL val="Commission Rate"><![CDATA[0]]></FL>

<FL val="Usage Unit"><![CDATA[Box]]></FL>

<FL val="Qty Ordered"><![CDATA[0]]></FL>

<FL val="Qty in Stock"><![CDATA[0]]></FL>

<FL val="Reorder Level"><![CDATA[0]]></FL>

<FL val="Handler"><![CDATA[eharrington]]></FL>

<FL val="Qty in Demand"><![CDATA[0]]></FL>

<FL val="Taxable"><![CDATA[true]]></FL>

</row>

</Products>

</result>

</response>

What can be used to get this field value?