My software company rents/leases my software to our clients.

They pay per user per month, indefinitely.

For that they get: all upgrades, and support

It works very well because there is not a huge capital outlay in the beginning,

and they don't end up with licenses that they bought but are not using because of downsizing etc.

Every month we get the latest count of licenses, and that's what we bill.

For us it brings in consistent, regular income, which is great for budgeting.

We certainly feel justified in doing this as the client has more manageable payments,

and all new features we build in (currently every month) they get, so they never feel like they're on the old version.

Plus it means we don't need to support more than, at most, 2 versions at a time 🙂