Can I transfer programs from mac to mac?

For most any program, yes you can.

 

Not necessarily. Applications that have serial numbers can't legally be transferred. Lots of other apps are only licensed to one machine.

 

Somewhat agree but for many application you can just copy the the Library and preferences files to get around that. Another option is to use the Transfer-from-Another-Mac feature. General consent is though that Applications can be copied unless they depend on external libraries installed by the accompanying installer.

 

If applications where bought at Mac App Store, they will not be run at another Mac (if developers added receipt validation, however, as I saw, not all of them doing that properly) - they will require to enter valid iTunes credentials to download the receipt.

Other applications can require license code, however, since it is stored in file somewhere, you can just copy that file. Anyway that will not guarantee that everything will work.