I have an iMac and have purchased several apps and other programmes. I am considering buying a MacBook Pro. Will I have to re-purchase these apps and programmes?

If you have purchased the apps at the Mac App Store, you can install them in all your Macs as many times as you want for free, so you won't have any problem.

If you purchased them from another source, you have to contact with the developer in order to know if you can use the license you have now in múltiple computers.

Note that during the initial setup of your new MacBook, it will ask you to restore data from another Mac, so if you do it from the iMac, you can transfer your applications to your MacBook > http://pondini.org/OSX/SetupLion.html You won't have any problem transferring the apps by this way, but if the license you have now for the applications only allow you to use them in one Mac, you won't be able to activate them