the license keys sit on one computer - your signed application will run on any blackberry. you get a couple of billion keys (you'll never run out). it's a one time payment and from then on you can develop as many applications as you want and sign as many times as you want.
every time you build a new version of your app and want to run it on a real device you just need to code-sign it first
new job doesn't allow a public profile - please do not contact this user with questions, you will not get a response. good luck!