Only as important as you make it. If it's important to you, then it's important. It doesn't make nor break authenticity. You should always have any used bag authenticated, and if you sell one, the same is true. Authenticate it before you sell it so that potential bad buyers will hopefully move on to another seller to scam.
Thank you so very much! Looking to buy something for myself to keep. Possibly used due to prices. I just didn't know if you needed the hologram or tag to know if it was real. Thank you again for answering. I really appreciate it!