If you are trying to access Project Server 2007 PWA (or through Project Pro) and you get an message stating the 'Trial Period Expired' there are two (2) most likely valid explanations:

(1) You are using a Trial Project Server 2007 license and your 180 days has passed.

(2) You installed Project Server 2007 SP2 (from MSFT - that had a bug in it)

If you fall into one of these categories you can Manually resolve this issue my entering in your VALID product key on the 'Convert License Type' page in SharePoint Central Administration.  If you do not know your SharePoint Central Admin url you can log onto the the Application Server and go to Start-->Programs-->SharePoint -->SharePoint Central Admin.

To manually enter in your VALID product key, do the following:  (as an Admin to the App box)

  1. Click Start, point to All Programs, point to Administrative Tools, and then click SharePoint 3.0 Central Administration.
  2. Click the Operations tab.
  3. Click Convert License Type.
  4. In the Enter the Product Key text box, type your product identification number, and then click OK.
  5. The License Synchronizer Job will run on all computers in the farm after a few moments. After all the computers have updated their license from the timer job, the Convert License Type page will reflect the correct license.

If you do not have your product key, you can retrieve it by logging on to the Volume Licensing Service Center (https://www.microsoft.com/licensing/servicecenter/home.aspx).

For more detailed information, read the MSFT kb article at:  http://support.microsoft.com/kb/971620.

Hope this helps.
-Jacques