You can use the same Studio One Product Key Activation for several User Accounts on the same physical host computer.
1. Install the Studio One 4 software on the ADMIN Account for this computer, following the instructions in this Guide: [2a] Studio One 4 : Register Software Purchase and Download Installer
2. After the software has been installed, launch Studio One while still logged in on the ADMIN Account.
3. Activate the software (if this is a brand-new install). For reference on Online Activation, follow this Guide:  Software Activation (Online Computer)
4. On the menu bar, go to Studio One > Studio One Installation and choose the following options:
5. In the "Install From:" field, use the drop down and select "Download from PreSonus Account" or press "Select" to choose files from your computer.
6. In the "Install To:" drop-down list, click on the drop-down arrow and choose the: C:\Users\Public\Documents\PreSonus\Studio One option.
7. Make sure "Show Packages" has a check mark in the box.
8. Close Studio One.
9. Log out of the ADMIN Account.
10. Log into the new User Account that you wish to have setup for Studio One 4 usage access.
11. Start Studio One 4.
12. Accept the Studio One End License User Agreement.
13. Now you will have all Sound Sets and demos working in this User Account.
14. Repeat Steps #8 through 10 for any other non-ADMIN User Accounts on this host computer.