The following might work for you:
You should direct questions about using the software in the After Effects forum. Here is a link...
Moving this discussion to the Premiere Elements forum.
You can remove the Adobe watermark from a tryout project file (project.prel) after you purchased the product.
However, you cannot remove the Adobe watermark from an export of the tryout version.
To remove the Adobe watermark from a tryout project file (project.prel), open the project.prel in the purchased product. The classical answer is then to go to Timeline Menu/Delete Rendered Files and click on it. The Adobe watermark should be gone. Some of us have found that the Adobe watermark automatically disappears from the tryout project.prel when it is opened in the purchased product.
Please review the above and let us know the outcome. Any questions or need clarification, please do not hesitate to ask.