Checking the tariff plan

I want to make tariff plans for my software, how can I check the tariff plan through a get request? there is information in the help, but it is for site users, and I need to get a list of user subscriptions in JSON format as a response to a get request in my program …
in the program, you need to log in via login / password - the program transmits the request and receives a JSON list of valid user subscriptions in response.
Help release the site’s response …

p.s. Google translator