About:
This add-on sends out an alert and/or email X days before a user upgrade is about to expire, with an optional second notification once the upgrade has expired.
Purchased non-recurring upgrades also get a 'Extend Upgrade' button so members can renew their upgrades without interruption.
Also, expired upgrades may be viewed as a list.

Please note that this add-on adds one column to the xf_user_upgrade_active table in order to keep track of those who have been notified.
It also adds one column to the xf_user_upgrade table in order to allow different Expiration Notification number of Days per User Upgrade.

Feature List:

• Send alert and/or email upon upgrade purchase.
• Send alert and/or email X days before a user upgrade is about to expire. May also be applied to recurring upgrades (subscriptions).
  • This value is set via the User Upgrade creation/edit page and allows you to send out, for example, an expiration notification 3 days prior to a one month upgrade expiring, and 21 days prior to a one year upgrade expiring.
• Send alert and/or email once upgrade has expired.
• Optional "Extend Upgrade" button for non-recurring upgrades. This button is available on the user's purchased list to allow for early renewal thus preventing the downgrading and then re-upgrading of the user. No longer will your members need to wait for an upgrade to expire before they can re-purchase it.
  This button will only be available if the upgrade details have not changed since it was first purchased (such as cost, length, user groups, and whether recurring) as they must remain the same in case the payment is reversed and the end date has to be adjusted accordingly.
• If an upgrade extension payment is reversed, the upgrade expiry date is adjusted accordingly.
• Expired upgrades are displayed as a list that is searchable by user name (now default in XF 1.4).
• Support for Gift Upgrades by @NixFifty . Used together with this Expiring User Upgrades, you can encourage a gifted user to extend their user upgrade when it has almost expired and increase your revenue as a result.