Database sessions completely occupied license limit

Hi All,

My customer License limit is 20 users

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                Action                                                                               Database Current Session Status

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5 users opened NAV 2009 Classic                                                          5

One particular user opening NAV via VPN connection                          20 

When particular user connecting via VPN to NAV, database session completely occupying. I tried keep delete the particular user session, still filling the license limit. 

Please advise if anyone face this issue.

Thanks

Vinoth