Update question, please

I received an alert in my parallels today that there is an update available. I have a few questions. If I update, will everything work just the same? Is it the same activation code and so forth of the hardcopy version I bought? Secondly, it says to remember to reinstall the parallels tools in the Guest, and I am not sure what that means - I am not parallels savvy, and just bought it to run one program, so I dont do anything else with it.

Thank you so much. I use parallels for my job, so I am afraid to update, mess something up, and get in trouble at my job.

 

It should work, without problem.
Also, in "the worst case" you can uninstall and revert back
P.S.
"The worst case" is incorrect permissions, some custom Mac applications installed etc.