Let's say you successfully create a Delaware corporation. It exists. It has a US tax ID number. It has a bank account. It has a merchant account. All of the stuff you want to do business. In other words, stipulate complete success in achieving your business objective.
Here is what the tax part of your plan will look like:
1. Money comes into your corporation via the merchant account.
2. After paying expenses, you have money left over inside your Delaware corporation.
3. That -- to the U.S. government -- is taxable income.
Crap. So you have to pay U.S. tax on the money flowing through the merchant account? You don't want to do that. How do you get the money out of that Delaware corporation?
A. Dividend. No good. First you pay corporate income tax on your profits in the Delaware corporation. Then you pay a dividend to the shareholder--you. The default U.S. rule is that the Delaware corporation has to withhold 30% of the dividend payment it makes to you. There are sometimes ways around this.
B. Loan to you. No good. First you pay corporate income tax on your profits in the Delaware corporation. Then you loan it to yourself. Only marginally better because at least you don't have the 30% withholding tax on the dividend. But you have to pay the loan back, with interest. And the interest payment back to the Delaware corporation is taxable income to the Delaware corporation on which it has to pay income tax.
C. Tax-deductible expense. Aha. Now we're getting somewhere. The Delaware corporation has a business expense that it pays. This reduces its taxable income, thus reducing tax. E.g., $1,000 of profit in the corporation, and you perform services for the corporation and the corporation pays you a consulting fee of $950. Hey presto! New net profit is $1,000 - $950 = $50 profit in the Delaware corporation. Tax liability is next to zero. Yay.
Item C is where the fun and games are. This is called transfer pricing in the tax geek world. (Yes, in fact I do own the domain name taxgeek.com and I can't figure out what to do with it.) In order to do this successfully you have to navigate through complex tax rules to avoid tax withholding on that $950 you paid yourself (analogous to the 30% withholding on that dividend). You have to navigate through the transfer pricing rules generally.
It's awesomely hard. And expensive. The reason is simple: you're trying to drain taxable profits out of a high tax country, thus depriving the U.S. government of money. They are quick to call "Bullshit" on these types of plans. So you have to do it right. And many, many other countries have their own transfer pricing rules.
When you said "Can I charge the US company the same amount it makes on (re)selling a monthly subscription?" you were really talking about something that looks like transfer pricing.
Related party transactions. Meh. Hard. That's what we are talking about and they get looked at by the government. A lot.
Advice: set up the Delaware corporation so it buys your product, marks it up, and resells it. Leave a little profit on the table in the USA and pay tax on it. As long as you are a small potato floating in the great crockpot of life, you are probably going to be OK. :-)
Further advice. You MUST prevent the USA from thinking that you (from wherever you live) are doing business directly in the USA. This is variously called a "permanent establishment" (in treaty lingo) or other similar ideas.
Further advice. The accounting and tax return work for this is going to chew up a lot of your profits. If you get a cheap quotation for tax return work, run like hell. People who are competent in international tax work are rare, therefore expensive. And the price of incompetence is usually big financial penalties from the government -- like $10,000 at a time for not filing the correct documents.
That is why I tell people to concentrate on running their business correctly and not to get clever to save taxes in the international area. Set up as simple a structure as possible to eliminate as many possibilities for error as you can. Like they say in AA, if you don't take the first drink you don't get drunk. If you don't set up that extra-fancy tax-saving device, you can't fuck it up and get hit with a penalty.