It may be claimed to be a free game, but this is in the TOS that you have to agree to:
You may create an Account without paying any registration or subscription fees. However, Gala-Net may charges fees to access and acquire certain game items or participate in game activities on gPotato. ANY APPLICABLE FEES AND OTHER CHARGES ARE PAYABLE IN ADVANCE AND ARE NOT REFUNDABLE IN WHOLE OR IN PART. Gala-Net may, from time to time, modify, amend, or supplement its fee and billing methods, and post those changes on the Terms of Service page or elsewhere on the Website. Such modifications, amendments or supplements shall be effective immediately upon posting on the Website. If any change is unacceptable to you, you may cancel your Account at any time, but Gala-Net will not refund any fees that may have accrued to your Account before such cancellation, and we will not prorate fees for any charges. For further information please refer to billing.gpotato.com.