This is a benefit of buying a product new. The original owner can choose not to transfer the license to you, they are under no obligation to do so, if they are using the software and even upgraded it, the original license stays with them.
As the product is used, you are now the new 2nd (or later) owner of the hardware, we are not obligated to provide this to you, nor can we demand the previous owner transfer the license to you.
You have a few options:
- Purchase a license of Studio One from the web shop
- Use Studio One Prime (Free in your account)
- Use another DAW