I don't know about render.com, but as long you have a HTTPS domain, you can just use any domain. \
Also, I think many services will notify you about changes of their pricing, so you can just back up the server and move them somewhere before something going up. \
Some good info about Vaultwarden is in the wiki, including some installation source, there are docker, binaries, and rust, so you can pick one of them.
I don't know about render.com, but as long you have a HTTPS domain, you can just use any domain.
\ Also, I think many services will notify you about changes of their pricing, so you can just back up the server and move them somewhere before something going up.
\ Some good info about Vaultwarden is in the wiki, including some installation source, there are docker, binaries, and rust, so you can pick one of them.