Question: I had money sitting in a mobile payment wallet that expired after a year of no activity. The app now says the balance is gone. Can the company that ran the wallet just keep unclaimed funds like that?
Answer: No. Non-bank prepaid instrument issuers cannot appropriate unused customer balances even after the instrument's validity lapses — your outstanding balance must be refunded to the source account or otherwise returned to you on request. The issuer can only treat the balance as its own after three years of continuous dormancy.

Supporting evidence:
title: rbi.org.in/BS_ViewMasDirections.aspx
quote: In case the PPI holder approaches the PPI issuer for refund of such amount, at any time after the expiry date of PPI, then the same shall be paid to the PPI holder in a bank account Non-bank PPI issuer cannot transfer the outstanding balance to its Profit & Loss account for at least three years from the expiry date of PPI
context: od mentioned on the card), the customer shall have the option to seek replacement of the card. 13.2 PPI issuer shall caution the PPI holder at reasonable intervals, during the 45 days’ period prior to expiry of the validity period of the PPI. The caution advice shall be sent by SMS / e-mail / any other means in the language preferred by the holder indicated at the time of issuance of the PPI. 13.3 Non-bank PPI issuer cannot transfer the outstanding balance to its Profit & Loss account for at least three years from the expiry date of PPI. In case the PPI holder approaches the PPI issuer for refund of such amount, at any time after the expiry date of PPI, then the same shall be paid to the PPI holder in a bank account. 13.4 Bank issuing PPIs shall be guided by the instructions on Depositor Education and Awareness Fund (DEA Fund) issued by Department of Banking Regulation, RBI, vide, circular DBOD.No.DEAF Cell.BC.101/30.01.002/2013-14 dated March 21, 2014 , as amended from time to time. 13.5 The PPI Issuer shall clearly indicate the expiry period of the PPI to the customer at the time of issuance of PPIs. Such information shall be clearly enunciated in the terms and conditions of sale of PPI. Where applicable, it shall also be clearly outlined on the website / mobile application of the PPI issuer. 13.6 PPIs with no financial transaction for a consecutive period of one year shall be made inactive by the PPI issuer after sending a notice to the PPI holder/s. These can be reactivated only after validation and applicable due diligence. These PPIs shall be reported to RBI separately.

13.7 The holders of PPIs shall be permitted to redeem the outstanding balance in the PPI, if for any reason the scheme is being wound-up or is directed by RBI to be discontinued.
14. Transactions limits 14.1 The PPI holder is allowed to use the PPI for purposes within the overall PPI limit applicable. PPI issuer shall decide on limits considering the risk perception of the holders as per its risk management policy. 14.2 All financial limits indicated against each type / category of the PPI shall be strictly adhered to. 14.3 Handling refunds Refunds in case of failed / returned / rejected / cancelled transactions shall be applied to the respective PPI immediately, to the extent that payment was made initially by debit to the PPI, even if such application of funds results in exceeding the limits prescribed for that type / category of PPI. However, refunds in case of failed / returned /