I think so the message that you are getting for Trial Expired is for Lightroom Mobile, you may pause it from top left corner.
Also please try to open the image in Photoshop and see if you are able to see the Watermark.
Try to create a new watermark with another font and then export the image and see.
I did change the font ,but it didnt work .Also how do I pause trial mobil lightroom I could not figure how to do that Thanks
Please create a New Watermark with a completely new font and then check.
To pause Lightroom Mobile, click on your name on the Top left corner and there should be a dropdown, there you will see the option to Pause.