Variant 1
For security reasons, the authentication of a device on which stashcat is not used for more than 4 weeks expires. The account will then be logged out on that device and the login details will need to be re-entered.
Variant 2
The organization has set a limit on how many devices per user can be logged in at the same time. For example, if this limit is set to 2 and you connect to a third device, the device you logged in first will be logged out.