>>>True, but you can have a test within VFP application for the inactivity and release application (and update login tables) for long periods of inactivity.
>>
>>I know that it's possible, but it's a pain in practice.
>
>What are the alternatives?

Do what web apps already do: send a keepalive signal. Maybe once in 4 minutes or so, a timer should update the LastSeenActiveAt datetime field in your login table. Then, serverside, you check for that field being older than 10 minutes or so (give them some chance for one or two failures - the app may be busy and the timer may not have fired).