Since 2.5.0 we have added States and Region support in RD-Subscriptions, this functionality has been disabled by default so current customers aren't getting surprised during an upgrade. To enable the sates and regions in the component, you need to navigate to the Configuration (Options button) for RD-Subscriptions. Enable it and you will see an extra tile and menu item in the backend overviews.

 Importing States in RD-Subscriptions

As the component will not be shipped with regions and states, you need to import these states first before you can use them. When you have enabled the states and regions option, you can navigate to the States option in RD-Subscriptions. 
The screen will be empty by default, now you can start importing 4100+ regions and states from MaxMind. (Keep in mind that this may take a while!)

If you left the original counties as in the original installation, all relations are being created and you're ready to go. 

Important Information:
As soon as you're going to add/edit states, you can not click the import button again.
When clicking the import button again the database wil be truncated and all states and regions are being removed to start the import again.

Where is the component affected?

For those who have template overrides, you may check these overrides to make sure it is working in your installation also. 

1. site/layouts/account_fields.php
2. site/views/checkout/tmpl/default.php
3. site/views/checkout/tmpl/default_account.php
4. site/views/myprofile/tmpl/default.php