Downside to Forever Timeout in ASP.NET MVC?

As a user, when I see a "remember me" checkbox, I expect it to remember me -- not just when I close my browser, but when I come back to the site after a week.

So in my ASP.NET MVC application I am considering the following web.config values:

<authentication mode="Forms">
  <forms defaultUrl="/" loginUrl="/account/login" name=".ASPXAUTH" timeout="50000000" />
</authentication>

I plan to also have userIsOnlineTimeWindow="20" to still have decent stats about who is online. I also plan to setup a machineKey so that the user isn't kicked off when IIS recycles.

Thoughts on this setup? My开发者_Go百科 biggest concern is that it will hog up resources -- but will it in a stateless MVC app? Isn't that actually related to the sessionState timeout variable as opposed to authentication timeout? And sessionState is no longer relevant in MVC? I've seen conflicting information and am trying to get to the bottom of it.

Also, if I take this approach, I assume that this should also take care of the user who fills out a form for a long time before hitting submit and they lose their work. I've seen posts related to that, but am trying to solve two problems at once (keep alive while viewing the page plus also keep alive for days if I said 'remember me'.

One issue I see is that even if the user doesn't say "remember me" it will still remember them until they close the browser. (To me that's within user expectations.) The other issue is that I may need to perform extra checks on IsApproved and IsLockedOut per http://scottonwriting.net/sowblog/posts/11167.aspx.

Thoughts? Particularly on the system resources issue. Thanks.

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FormsAuthentication is stored as a cookie in the client's browser and will not use up any resources by itself. The timeout setting there does not change how long something will be kept in the server's memory or anything to do with the regular session storage.

If you rely solely on the user ID/name you get from FormsAuthentication (HttpContext.User) then yes, there will probably be issues with administering user accounts like you point out. It would be a good practice to look up the actual current user data once per request.