This filter controls whether discount codes should only be applied to certain levels. By default, this is set to true, and discount codes are checked to see if they apply to the membership level passed. Return true if the code can be used with the level supplied or false if not.

apply_filters("pmpro_check_discount_code_levels", true, int $dbcode->id);

Parameters

bool (true)

$dbcode->id

int

Source

File: https://github.com/strangerstudios/paid-memberships-pro/blob/master/includes/functions.php