marking paid by customer

Hi evaluating the product. I've set up some trial invoices so i can see what my customer is receiving- has my customer got the option to click PAID without proof of payment? I have received an auto email telling me the invoice is paid. Is this how the product work or am i doing something wrong....
Looking forward to your comments

Hello Pat,

That is right. You need to ask your customer to add proof of payment. If you are accepting payments through Stripe or other online payment methods there are Apps that can provide you the proof of payment without asking your customers. You might want to check this link for payment methods.

akaunting.com/apps/categories/payment-method