You cannot simply load a packet of your UPC/EAN codes in your DYMO label printer, you have to do that one-by-one, a very time consuming activity.
EANnummer.com offers you a UPC/EAN to DYMO conversion service for "ready to install DYMO codes packages", incl. an extended installation and use "how-to-do".
The use of the UPC/EAN codes from GS1 can generate a huge potential risque for your company if you use these numbers to identify production processes, product recipes, storage layouts, staff and visitors identifiers, safety key locations, etc, etc. because they are public information for other GS1 members.
Also do you loose your GS1 numbers if you stop paying your high yearly GS1 membership fees.
The UPC/EAN codes of EANnummer.com are really unique, they will never recycled, no yearly fee, they stay private as long as you wish and you own them till the end of time.