We have a free plesk licence that came with the server but we are changing the os as the datacentre wouldnt install the one we wanted this will void support we get from them tho. So I need to know the following.

Can I just write down the key number and then install the new plesk and enter this key and its licenced again?

I also want to know if I have to stick to the versions of software that plesk likes eg. mysql3.x I would like to use latest stable instead and manage my server from the command line the plesk ideally I just want to use for user/email/domain management.

Very easy to transfer licences. Often we get the wrong licence from a data center so we replace with an existing one from another server until a replacement is issued. When you install a key, it does email Plesk so they do know. With Plesk you can upgrade all software. You can upgrade OS from 7.3 through to Fedora Core 2, install MySQL 4, upgrade to the latest PHP version etc. It's pretty flexible.

when you say it email's plesk will that mean I will be in trouble for installing it again with the same key? sorry I am a bit confused.

If it's teh same server, you'll be fine.

yep same server same ip, thanks for your help.

aha same problem for me