Licenses are linked to install path, domain, and IP address. We can enabled multiple IPs and domains per install, though this is typically only done for multi-company licenses but there may be something we can do to acomodate you.
Only what's necessary to protect licensing.
By lifetime are you referring to our lifetime owned license? That license includes support and updates for life, so there's no need to purchase anything else to receive support and updates.
Owned licenses include 1 year of support and updates, after which you may optionally purchase support and updates on a yearly basis.
Releases follow semantic versioning, and patch releases are always free. As an example, if you are running 3.0.0 and we release 3.1.0 but you are not current with your support and updates at the time of that release you may upgrade to any 3.0.x release, but you will need support and updates to upgrade to the 3.1 minor release.
You can install Blesta anywhere you'd like.
You can certainly do that if you're comfortable with a little PHP. Or you can create static HTML pages that simply link to pages within the Blesta order form.
A number of users are currently running Blesta on nginx. Kudos to cloudrck.
Security is by far our top priority, so we make a strong effort to releases security patches as fast as possible. The average turn around time varies depending on the severity of the issue, but can range between a few hours to about a week.