As per RBI guidelines, the details shared by you earlier were valid only for 1 year.
In case you have not shared any Identification number of select set of documents on the Freecharge App, your Wallet was deemed Min KYC from 1st March 2018 as per RBI guidelines and hence, your Wallet will expire on 28th Feb 2019.
In case you have signed up on Freecharge after 1st March, your Minimum KYC is valid from the date of submission of details to a year after the date of submission. E.g. If you signed up on Freecharge on 2nd March 2018 and shared KYC details on 15th March 2018, then your KYC will expire on 14th March 2019.