An annual license is a lower annual fee and will always give you access to the latest version. If you ever choose to not renew, your install will automatically revert to the free Starter Edition.
A lifetime license is only for the version (and its sub-versions) available at the time of purchase, however the license is yours to keep and will always be valid.
At this time we only accept credit card payment via Paypal.
Typically just one, however you can install your license on multiple servers, provided it's accessed from the same URL (for example, in a load-balancing scenario.) You can also have a single install that's accessible from multiple URLs.
There is no restriction on number of users, only number of installs.
At this time we're not offering any discount program.
Once a license has been issued, we're unable to offer a refund.