When I retrieve response from query http://api.rapidshare.com/cgi-bin/rsapi.cgi?sub=getaccountdetails_v1&type=prem&login=MY_USERNAME&password=MY_PASSWORD, among other variables, I get .............. validuntil=1251783433.........., which should tell me the exact expiration date. My question is how to convert this integer to normal date time format.
That number (1251783433) is known as Unix time. Most programming languages have methods to convert from Unix time to a date/time format.