You do not need to add anything, but you most certainly CAN! I paid a seller on here to create a simple software for me to easily produce HQ PDF Licenses to tell buyers what they can and can’t do. You can do this too using something simple like a graphics program or even a text editor. Doesn’t have to be flashy a simple Text File included with your fiverr name should suffice. I encourage you to get creative and do your own thing. YOU are the boss of your business bro, ultimately it all comes down to your design process and whatever gig you have. If a customer buys a $5 logo from me, chances are I’m not giving full copyrights, they can order that extra and I will include a license file or create a copyright file. Another splendid idea would be to get a professional looking invoice from graphic river or have another seller create you an invoice template to include with your delivery to the customer. The Invoice should include an invoice number ( You can start at one and go forward), Your Logo somewhere large enough to be visible and a nice summary of the purchased services!