You can transfer a license between machines as much as you see fit. If you are doing it multiple times each day though you are essentially trying to replicate manually what a floating license does without effort. You would definitely want to look at the floating license system at some point.
For the PDM Standard licenses, these by default are floating licenses. You would get one PDM Standard license for each SOLIDWORKS Professional (or Premium) license you have but they would be setup on a floating network server to move between machines as needed. So, having 3 seats you can still have distinct logins for more than 3 users. Users that don't have a license won't be forced to check stuff into the vault since they don't have a license but they will need to get a license back to interact with the vault in meaningful ways (check-in/check-out).