For the seller it is different (because we care about LTV), but typically the $900 expenditure is "X services, Nov. 17 - Dec 17". They are loyal customers, but

For the seller it is different (because we care about LTV), but typically the $900 expenditure is "X services, Nov. 17 - Dec 17". They are loyal customers, but it isn't as though they are even breaking the spirit of the rule. [Example: if they bought $10 worth of pens, no one would ask whether they calculated the amortized lifetime cost of needing pens and issued a bulk approval form. Lots of real life expenses are recurring.]