Irule problem "contains then insert"

Do you get any error when adding the iRule to the system? Do you get any error when the iRule is executed?

I don't see any major error in the iRule, except the double {. However, that shouldn't cause problems.

Try add some log messages, like this:

when HTTP_REQUEST {
  log local0. "[HTTP::uri]"
  if { [HTTP::uri] contains "native-billing" } { 
    HTTP::header insert "X-Version" "'9.0'"
    log local0. "Header inserted"
  }
  log local0. "Headers: [HTTP::header names]"
}