I frequently do not have an internet connection. Can I still use Photoshop and Lightroom when disconnected?
yes. you just need to be connected for initial installation/activation and then periodically connected.
See also Creative Cloud Help | Creative Cloud / Common Questions
No, the desktop applications in Creative Cloud, such as Photoshop and Illustrator, are installed directly on your computer, so you don’t need an ongoing Internet connection to use them.
An Internet connection is required the first time you install and license your apps, but you can use the apps in offline mode with a valid software license. The desktop apps will attempt to validate your software licenses every 30 days.
Annual members can use the apps for up to 99 days in offline mode. Month-to-month members can use the software for up to 30 days in offline mode.
Thank you.