Expired trial when service not started (version 4.5)
If one instance shows that the trial is expired and you don't believe this to be true, it's worth checking that the SQL Backup Agent service is running for that instance.
Go to Contol panel -> Administrative Tools -> Services and right click the SQL Backup Agent service (for the corresponding SQL Server instance) to check the Log on account and to make sure it's started and the account it's running under has permissions to write to the registry.
SQL Backup Project Manager
Red Gate Software