All of our plans have a connection limit associated with them, with the Free Plan's limit being 30. If you need more connections you will need to upgrade to a plan that offers more connections.
If you want to look at your active connections you can use the CLIENT LIST command.
If there are connections you want to "kill" you can use the CLIENT KILL command.
It is always recommended to use connection pooling, otherwise each request opens a new connection. This exposes you to many possible momentary problems that could prevent the opening of the connection. In addition, if you make many requests, you will be frequently opening and closing connections, operations which might fail from time to time.
Using connection pooling, you will be opening a few connections that will serve all requests, and will not close after each request. This eliminates the problems above and will also give you better performance because no time will be wasted on opening and closing connections.