We've used OpenNebula in production for five years now. 

I have been using OpenNebula for four years.

I've managed an enterprise production installation of OpenNebula Enterprise for roughly four years.

I've been using OpenNebula for about six or seven years.

We have been using OpenNebula for the past one and a half to two years.

I have been using the solution for one year.

We've been using OpenNebula for three years now.

I've used the solution for around three years. 

I've been working with OpenNebula since 2016, but most of my experience with it started in 2017. I've worked with the solution within the last eighteen months when a client requested an OpenNebula installation.

We've been using this solution for over two years. 

I have worked with OpenNebula for more than three years.

We are community champions for OpenNebula. We have been using OpenNebula for quite some time. It's been around seven years.

We have been using OpenNebula for more than five years.