For internal search terms, a company wants to give credit to the original keyword used...

 Business Requirement: The company wants to ensure that the original search term ("Mobile") receives credit for the purchase, despite subsequent searches.

 Understanding Merchandising eVars: Merchandising eVars are used to attribute success events (like purchases) to specific values captured earlier (like search terms).

 Allocation and Expiration Settings:

Original Value (First) Allocation: This setting ensures that the first value captured (in this case, "Mobile") remains attributed to the visitor, regardless of subsequent values.

Expiration Setting: Setting the expiration to the purchase event ensures that the value ("Mobile") remains active until the visitor makes a purchase.

 Explanation:

Configure an eVar as Merchandising Variable: This allows tracking specific values like search terms in relation to product views and purchases.

Original Value (First) Allocation: Ensures that the initial search term ("Mobile") gets credit.

Expiration to Purchase Event: Keeps the eVar value until the purchase is made, ensuring accurate attribution.

 Verification: According to Adobe Analytics documentation on Merchandising eVars, using Original Value allocation with appropriate expiration settings ensures correct attribution of original search terms to final purchases (Adobe Analytics Implementation Guide).