Instead of using instagram username, please use instagram ID as basis for account subscription.

Instagram account subscription in 4k Stogram is based on instagram account username. This is not good because sometimes, instagram users change their usernames. Instead of using the username, I suggest using the instagram ID which is a unique number assigned to each user. The username displayed could just be a dynamic value based on the instagram ID. This way, even if the user has changed his or her username, the subscription is still valid.