I've posted a new build for Subscription Tools in the downloads section (members only).

New Functionality Includes:-

• Added the language parameter back in with suitable adjustments to upper casing and a fixed language list. See more information here.
• A new option has been added to require a shipping address. This will allow administrators to handle sales tax in PayPal. This option is disabled by default.
• A new parameter is passed to PayPal (invoice), this will include . This will allow administrators to easily lookup the username of the subscriber.

Thanks again for all your feedback!