Payments directly to Nepal can be done by direct bank transfer, but sometimes give complications. And refunds from Nepal are not possible.
To make things easy we have a support organization in the Netherlands for handling International payments to us.
Through them, we can accept SEPA direct bank transfers, PayPal payments (also for various credit cards), BitCoin payments, and a few other localized payment options.

New customers we ask to pre-pay for the templates.
For existing customers we can either ask for a prepayment or we will invoice after the month has turned over.
If existing customers pay us consistently nicely within the first 2 weeks after we invoice them, then there is no reason for prepayments.
If existing customers are less regular in paying their invoices, then we ask for either prepayment per template, or for a deposit amount from which we deduct built templates.