Levy of service tax would depend upon the currency in which you are receiving funds. If the fee is received in foreign currency then it would amount to export of services and hence not chargeable to service tax.
In case you are going to receive in in indian currency, then it would be difficult to claim exemption and you would have to collect tax.
You will also have to register yourself with DGFT for export of services. Get an IE Code, declare to your banker and then receive funds from abroad.