How could I stop someone from recreating my online service

I am developing an online service (an application for Windows).
I understand that I can copyright the software itself.
However I would like to know my options with respect to protecting the security technique that this service will use so it cannot be immediately replicated and exploited by another party.
I read about Patents however I assume I would require an international patent and there is no way I could afford this.
Do you have any advice on how I could protect this product both here…
How could I stop someone from recreating my online service

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