If you already running the max nodes on Digital Ocean here is a way to get 10 more for free 30 days.
Use this link to get the free $50 credit https://www.vultr.com/?ref=8191464
and follow the amazing guide made by Christian Busch here on medium https://medium.com/nknetwork/setting-up-a-nkn-miner-in-5-minutes-and-run-it-free-for-2-months-with-digitalocean-76bafcd82ae8
You can follow his guide exactly you just need to first type: apt-get install sudo
You can get a node as cheap as $2.50 monthly!
I am currently running 10 nodes and it still free after many days 