Q - Can I save applications on a 4.0 farm, and then load them in a 4.5 farm?

A - Yes you can!, You'd have to consider that all domains/groups/users that have access to the applications, must also exist in the new environment! This doesn't not mean the application won't be saved in the new environment, it's just missing the user/group access list.

Q - I get: 'License Expired' contact support?

A - Follow this link for a detailed solution.