Hello and thank you for leaving this message on Expert PDF support forum.
Please grand Expert PDF connection to the Internet in order to authenticate its licence with the remote service.
Add Expert PDF to computer protection program trusted list then activate the software again.
Keep in mind that the key number allows the package to be unlocked to one computer only.
If you are trying to use it on restored computer or computer with replaced part or operating system it will not work, so you need to contact the support team for assistance.
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