Because the software is owned by the user - it is same as buying a music or movie CD. How long would the CD work? Here a similar question to ask is how long would the Cloud Providers be available for "lifetime"? The current supported cloud providers are Hetzner, AWS Lightsail, DigitalOcean, Akamai Linode and Vultr. They all seem to be around for quite a while and so I expect product to keep working for forseeable future by which time a user can easily get the value for the price they paid for the product.
For sake of argument for "lifetime": even if some of these cloud providers go out of business the probablity of all of going out of business is low, and so software will keep on working.
I'm also expecting new cloud providers to appear over long period of time worth adding support for.
The site is well setup and the service known however what are your plans in the long term?