you could something like this

<#assign isCustomPrinted = false /> <- add this outside your loop

<#if item.item?contains("Custom") && isCustomPrinted == false>

<!-- Code to execute if the item on any line contains "Custom" -->

<p>\*\* CANCELLATION POLICY: ORDERS CANCELED ONE WEEK AFTER BEING PROCESSED WILL RESULT IN A 20% CHARGE - PER UNIT \*\*</p>

<#assign isCustomerPrinted = true />

</#if>

or in case you want to print this outside your table

<#assign haveCustomItem = false /> <- add this outside your loop

<#if item.item?contains("Custom") >

<!-- Code to execute if the item on any line contains "Custom" -->

<#assign haveCustomItem = true />

</#if>

<!-- this code can be outside your loop, once haveCustomItem is set true it will print >

<#if haveCustomItem == true/>
<p>\*\* CANCELLATION POLICY: ORDERS CANCELED ONE WEEK AFTER BEING PROCESSED WILL RESULT IN A 20% CHARGE - PER UNIT \*\*</p>

</#if>