One question. So basically we've inherited a project that uses toolset & was a licensed.
So what i've done is create a new new licence & id like to link to link it to the site. But i can find the option for a licence on the WP backend or a way to authenticate the new license.
You can register by going to Plugins → Add New and clicking the Commercial tab, then scroll to the Toolset section. You can unregister the existing one and then register the new one by taking a new key from your current account.
No that shouldn't affect in any way. And the process should take less than a minute. However, being on safe side is always a good idea, try on a staging site if you have any doubt.