In mathematics term N is a natural number as in the term of N + 1. N + 2. etc.

In general expression, N often is used to express "so many times that one has lost count on how many."

Just receive another email offer addressed to husband for a 150K upgrade to Ascend. No expiration date. This is the 2nd or 3rd time he has received this. The upgrade to Aspire shows up in his (and my) online accounts N times, and they are currently present again, after a few weeks absence. I have seen it at least 6 or 7 or 8 times since Aspire has been introduced.

Virtually everyone I know has seen the 150K Aspire upgrade in his / her online account under the Amex Offers many times. Most prefer to upgrade to Ascend first, as DPs show, upgrade from Ascend to Aspire would inevitably show up again.