Product Pricing - Clarity of Costs by including currency identifier
Proton Products are available internationally.
Your documentation says
" We accept cash payments in US dollars (USD), euros (EUR), or Swiss francs (CHF)"
For "Pass + Simple Login Lifetime offer" it displays $199 which is VERY AMBIGUOUS for a company with customers around the world.
In the absence of precision and clarity as to what currency this "$" sign is referring to, an Australian would read this as AUD, a Solomon Islander would read this as SBD, ..... which represents a significant cost difference to the customer.
PLEASE BE PRECISE in showing costs of your products when using DOLLAR SIGNS. IF YOUR INTENT IS FOR USD, then specify USD so that the customer knows what their account will be charged for the products you sell.

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Ann commented
When making purchases, it makes common sense to know what the purchase will cost, as well as making sure there are sufficient funds in one's bank account.