@NorthernLights
The subscriptions are tied to the Roku account (the account email), not your network connection. You can change your network connection (and swap between them) without losing access or going through additional logins.
When you connect it to your temporary network (hotspot), just go to Settings/Network/Setup Connection and point it to the new network. Roku devices are designed with portability/travel in mind so can easily switch between networks and locations.
Only real time you should have to login again to a subscription is if you remove a channel/app or you factory reset your device. Neither of these procedures are required or needed to simply switch between networks.
Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
Insignia RokuTV, Ultra 4660, Premiere+ 3921, Express 4k+ 3941, Streambar 9102