Can change the user group when user pay successfully ?

[chameron]

I am new to VM

I create a downloadable product.

Even after the transaction is successfully completed, the status of the order will be changed to "confirmed".

Now i want change user group

Ex : we have 2 user groups : not support and support

if pay successfully, move this user to support group , else keep user in not support group

So what module or plugin that help me to do this ?