You should not be required to sign in each time you open Studio after quitting the app; however, we have discovered an issue that can prevent Studio from saving credentials on the system keychain. We are happy to report that a quick fix is available for this issue.
To let Studio properly store your sign-in credentials:
Open a Finder window, click the Applications tab, click the Utilities folder, and click Keychain Access.
Alternatively, in the Mac menu bar, click the search icon () and enter keychain access.
In the top-left corner of the Keychain Access dialog, click the lock icon twice—once to lock it and a second time to unlock it, which will require entering your system password (not your Studio password) when prompted.
Open Studio and sign in.
After completing the steps above to unlock your keychain, Studio should correctly save your credentials so you don't have to sign in moving forward.