Hi,
Just my opinion Support through email and comments will be more user friendly. But if you interest to create your own Support systems then you have to work much, you have to validate Customer that they have purchased your item or not. You have to handle purchase code using Envato api from your side to validate a customer but email and comments support you don’t need to validate as Envato will provide you all information about this when email support you receive. When comments will post you will see that the customer has purchased or not (Purchased Tag will show).
Thanks