It depends which version of Hoster you have, Full or Lite and also which version #, you can find this from Help menu About Hoster.
Generally if you have the full version you are allowed to load a second copy of it on another computer (2 installs) if you have the lite version or already have 2 installs then you must un-install
but must do this whilst connected to Internet else MTU has no idea you un-installed.
Do not un-install your original program unless you have the original installation file or you will have no way of re-installing it.
If do not have the original and your version is 4.22.08 or later you can download it again from here:
http://www.mtu.com/upgrades/hoster.htm
If your version is prior to this then unless you saved a copy of it, to the best of my knowledge your out of luck and unless you upgrade will not be able to move it.
Having said that if you are using an earlier version than about 4.32 it may not run correct on windows 7 64bit computers.
If you have the installation file then on running it you will be asked to enter your original email and registration data for it to install, if you do not know this you should be able to find it from your account page.
Versions earlier than 4 you may have to put in a support ticket to move them.
Also read this link:
http://www.mtu.com/support/how-to-mo...ation.htm#NOTE