ASP.NET is permanently stateless while ASP (Active Server Pages) are designed to be stateful or stateless based on the implementation style. ASP.NET being stateless means every HTTP request made to the web application does not retain any information from previous requests by default. The server is not designed to maintain or retain session states from one request to the other unless explicitly configured to do so.
There are, however ways to maintain state in ASP.NET applications such as cookies, view state, and session state. It is upon the developer to decide if they need to make ASP.NET stateful. It is standard practice in modern web application development to make use of stateful mechanisms.