Hi @Revelt,
I apologise in advance on behalf of the IPS team for the delay in not only approving your queued topic, but to give you an answer to your question.
If you are planning on purchasing a self-hosted plan, then you can only run one live installation under that licence.
You are permitted to have a single test installation as well, however it cannot be run as an independent and/or active forum. In addition, IPS allows for an unlimited number of installations on "localhost" domains so you can test locally without restriction, but again, they cannot be live communities.
I hope this helped answer your questions.