PDF Expert 7 has a collection of stamps you can add to your PDF files. Moreover, you can create your own stamps with texts or images.
The option to add stamps is available as a part of the PRO pack. Learn more about upgrading PDF Expert to PRO.
Note: If you've previously bought PDF Expert 6, you can still use stamps, without additional purchases.
For the text stamp, you can type any text you like. To include the current date or time to your stamp, enable the Date or Time toggle. PDF Expert automatically updates the date and time on your stamps.
For the image stamp, you can select a picture from Photos.
Note: The stamp you create is available in the Custom tab of the Stamps menu.