Keyclone doesn't expire, the useage license is forever. At worst, you will need to transfer the license if you make changes to your hardware, OS or use a new computer, which is easily done through the transfer button in Keyclone.

They should always be able to connect to each other.

the only differences between versions is usually bug fixes and various features. Keyclone increments by letters, we are on v1.9h. It's been a while since 1.8 and will probably be a while more before 2.0, especially if Rob wants to get mean and start doing v1.90a. ;P