Upgrade path is mentioned below:
Network Performance Monitor (NPM)
Upgrade Path
Orion NPM 7.8.5 ⇒ 8.5.1 ⇒ 9.1 ⇒ 9.5.1 ⇒ 10.1.3 ⇒ 10.3 ⇒ 10.7 ⇒ 11 (there is a new beta release)
If you have additional pollers you will have to follow the same (but then it has different bits which needs to be used on additional poller)
And if you have other modules (SAM, NTA etc etc) installed on your environment please refer to the Compatibility Matrix mentioned below
Always check the compatibility matrix before you upgrade (you wont see NPM 11 yet, but then I have pasted posts related to NPM 11 below hence upgrade path mentioned by me holds good ):
Upgrade link mentioned below:
Links related to NPM 11:
https://thwack.solarwinds.com/thread/66158
Hope the above content helps