If you are a Mac user, were able to install your license, and then subsequently received the error "Your license is no longer valid. This is often caused by updating your system. Please re-enter your licence serial number," then please read on.

This is a known issue in OOTP 10.0.7. It will be resolved in the first patch, and is logged in our bug tracking as issue # 3120.

Until then, you can continue running the game by using the following workaround:

1. Cancel the dialog box with the error message. The OOTP main screen will display
2. Go to the Game Preferences screen.
3. Click on the button entitled Unlicense Game
4. Close OOTP.
5. Navigate to your OOTP application folder (by default, Applications > Out of the Park Developments > OOTP Baseball 10)
6. Rename the OOTP 10 program file to "OOTP 10 - old". (This file may be called "OOTP 10.app," depending on your settings. It doesn't really matter what you rename it.)
7. Download this file.
8. Unzip this file into the same location as the file you renamed. You should now have a new OOTP 10 program file.
9. Launch OOTP
10. Click on Enter a license key and enter your license.
11. You should be good to go!

Note: If you did not unlicense the game, it may tell you that all of your licenses are in use. If this is the case, you will need to release one or both of your existing licenses. You can release your licenses through the PiSD Web Store. See the FAQ here, and look for the question, "My license has got stuck what can I do?"