That you can exchange something for other currencies doesn't make it a currency. Currency is defined by its use as a medium of exchange. Non-redeemable purchas

That you can exchange something for other currencies doesn't make it a currency. Currency is defined by its use as a medium of exchange. Non-redeemable purchasable tokens could meet the definition of a currency. Conversion can be facilitated by exchange between users, rather than by the issuer. In this case, the issuer's sale price only sets an upper bound on the exchange rate.