The problem occurs because you are using Aspose APIs in evaluation mode (without applying a License). If you want to test Aspose.Words without the evaluation version limitations, you can also request a 30-day Temporary License. Please refer to How to get a Temporary License?.
Please also refer to the following article:
Hi Aspose team,
Our company bought the Aspose Total somewhere back in 2011.
Could you please check if the license is still valid?
Please provide me with email address I can send the license info for check.
Please post your license file via private message. In order to send a private message with attachments, please click on my name and find “Message” button. (see steps ). We will then investigate the issue on our end and provide you more information. Please do not share your license file publicly in this thread.