To keep your library account secure, you can only keep your bpl.org account logged in on one browser at a time. Logging in on a new browser will log you out of an old browser.
However, the BPL to Go app is designed to remain logged in. Logging into the app will not log out your existing browser session.
This only applies to your library borrowing account and does not extend to third-party apps and services like OverDrive, Hoopla, or other online resources.