can we claim August 2017 month itc in this month july 2018?

Yes you can avail the credit now. Once September 2018 return filed, then credit beyond 1 year would be lost.

sir If input is in july 2017 Now we can take input? Can I know time limit to take input ?

ITC can be claimed only within one year from the date of issue of tax invoice relating to supply. In any other case, the last date to claim ITC is earlier of the two below:

Before the filing of valid return for the month of September following the end of FY to which such invoice is related, or Before the filing of the annual return

Note: As per section 44, the last date for filing of annual return is 31st December following the end of the financial year.