Public invite-only scripts can only be published by Premium accounts. They allow their author to control access to his script, which entails that you must obtain permission from the author to use it, and that will usually require payment. Public scripts have been analyzed by script moderators and comply with House Rules, but you should not infer from this that TradingView endorses the script or its author.
Do not assume that paid scripts are superior to those you can find among the tens of thousands of open-source and free scripts in our Public Library. Some freely available scripts on TradingView probably outclass the majority of invite-only scripts, and many invite-only scripts are but thinly veiled versions of widely available indicators, with perhaps a few modifications which in no way make them necessarily more useful.
Some invite-only scripts are designed by authors who provide genuinely original work, but keep in mind that generating profits in trading is about much more than signals for entries. There is even a good case to make that scripts providing only entry signals add little value to a trader's craft or trading account. That is because entries constitute only a small component of a complete winning strategy. Other factors like risk management, position-sizing, trading frequency, trading fees, and many others must also be properly managed to achieve profitability.
Another aspect that you must manage properly to achieve profitability is yourself. You can have the best quantitative model in your hands to tell you everything you need to trade, but if you cannot manage yourself as a trader, you will not realize the system's potential.
Before paying for a script that purports to help you with entries and exits, consider who's proposing to sell you that script. Is he a reputable author? How does he answer the questions we hope you will ask him about how his system manages risk and determines position sizes? Can he supply you with a track record of past trades on a real account? What markets was the system designed to run on? Must you use leverage to trade the system? Was the system backtested? Can you see backtesting results on multiple markets? Does the vendor have a support forum where you can ask questions and share with other users of his products? Can the vendor refer you to other customers?
Pay attention to how a vendor talks about his products. Generally, the more assurance he demonstrates, and the more guarantees he makes, the more red flags should pop up for you. Knowledgeable traders understand that systematically and accurately predicting future outcomes is impossible. Nobody knows what the future will bring. Unexpected events often occur. Experienced traders often use a cautionary tone because they understand that any trading methodology is fallible.
Some types of invite-only scripts are intended to run automated systems, others may be designed to be used in discretionary trading. Before paying for a script, be sure you understand what its intended use is.
Some vendors offer a trial period where you can test their scripts. Successful trading relies on the law of large numbers playing out, which may require hundreds or thousands of trades in order to properly evaluate a system. While a trial may help you better understand what the script does and how to use it, it will not allow you to ascertain its validity with any certainty.
Can some paid invite-only scripts be useful to traders? Sure, but if you choose to delegate the responsibility of your trading decisions to a tool, we hope you will do so knowing that much more than access to a script is needed to become a successful trader.