You will want to do this before requesting a list on behalf of a user. This endpoint will return the user’s email address, the credits they have available, and whether or not they are subscribed.
In order to submit a task, the user must have enough credits, and they must be subscribed. If either of these are not true you should direct the user to Coldlytics to top-up their balance, or subscribe to a plan.
GET '<https://api.coldlytics.com/v1/user>'
{
"email": "richard@coldlytics.com",
"credits_available": 1000,
"is_subscribed": true
}