Yes, you can now upgrade from a SharpCap Pro annual subscription to a lifetime license. Just visit the lifetime license page and enter the email address used for your current license to get started.
If you do not yet have a SharpCap Pro license at all then you cannot buy a lifetime license straight away. Just buy a 1 year license in the normal way, check you are happy with SharpCap Pro for a few weeks and then follow the link above to upgrade. Don’t worry, you won’t pay more, since you will get a discount off the lifetime license to account for the price you paid for the yearly license.