Pdf with attachments having issues with watermarking

We tried with trail license and could watermark any pdf. But when we tried pdf with attachments (1.5 gb+) then it fails. How to handle it? Please let us know so that we can evaluate and think of purchase for a company.

Could you please provide more information about the specific Aspose product you are using for watermarking and any error messages you are encountering? This will help us provide a more accurate answer.