About Testgram Premium.
Premium is not available on this deployment. There is no subscription tier, no payment provider, and nothing to buy.
You do not. Every feature on this server is available to every account.
Nothing, because the feature is not implemented here. If a paid tier is added later it will be announced on the blog.
No. This deployment runs for private use and has no advertising, no analytics, and no paid third-party integrations.
See the main FAQ for how this server actually works.