I am not a lawyer, and you should seek out an actual lawyer for a proper legal consultation.
That said, the terms of the license seem pretty clear. You may cancel your subscription, at which point you are not entitled to future updates of the engine, but you can still use the version you have:
After cancellation of your Subscription by either you or Epic, you
will not be entitled to access or use future Versions of the Engine
Code or Assets that Epic makes available under the License. However,
cancellation of your Subscription will not affect your rights under
the License with respect to any Licensed Technology you have already
downloaded under the License.
However, your use of the existing version is still bound by the terms of the license, which further states that:
You agree to pay Epic a royalty equal to 5% of all worldwide gross
revenue actually attributable to each Product, regardless of whether
such revenue is received by you or any other person or legal entity...
Thus, you still need to pay Epic the royalties you agreed upon the release of your game regardless of whether or not you are still paying for the subscription. This applies for all forms of distribution, including self-hosting the game and selling it from your website. Failure to pay Epic on time will result in late fees being incurred, and possibly eventual legal action.
The license spells out the particulars of the royalty arrangement, including when you have to pay them and when you don't. "Gross revenue" is not your profit, it is the total amount of money your product generates before subtracting out other third-party cuts, refunds you may need to issue, et cetera. The license even gives an example:
The royalty is based on gross revenue from end users, regardless of
whether you sell your Product to end users directly, self-publish via
App Store, or work with a publisher. The following simplified example
illustrates the application of the royalty to gross sales: if your
Product earns $10 on the App Store, Apple may pay you $7 (having
deducted 30% as a distribution fee), but your royalty to Epic would
still be 5% of $10 (or $0.50).