ServiceNow is a classic Enterprise software play that I like to call "old, but new".
You take the same old software, with the same old processes, the same old salespeople and sales approach, and you make a new one that is a little shinier and (crucially) freshly made. Because you used your same old connections and investors to fund the development, you have a much better product than whatever cruft HP Service Manager, CA Service Desk or BMC Remedy have been pushing, simply because you haven't been fiddling with a product originally written in C++ in 1998 for 20 years.
Furthermore, your solution is comprehensive enough that it covers most of the existing functionality of the old products in the space, and it ticks all of the same compliance checkboxes too. So there's very little career risk associated to buying it. You even took the customer to the same old restaurant you used to take him when he was buying HP software from you!
Another popular example of this strategy is Zoom. What is Zoom? GoToMeeting/Webex, but new.
On the lower end of the market, there is more entertainment, because not everyone that had legacy products want to pay through the nose for the pleasure of dealing with an army of Service Now suits. This is where companies like Freshworks, Atlassian and ours (InvGate) come in.
Source: founder of InvGate, mid-market player in the same space