How do I set up a resub alert?

You can create an alert for resubs by adding another subscriber alert to your Alert Package. Then set that alert’s Display Condition to “Subscribed for at least” and enter "2 months" into the field to the right of the drop-down where you choose your Display Condition.
To display the number of months your viewer has been subscribed for in your alert, use the {amount} variable in the title or subtitle field.

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