Gst input credit?

if you registered right now all the gst charged you have paid for value of goods currently you have either as raw material or WIP or finished goods and age of invoice shouldn't be older than 12 month . As you are fall under service industry you would hardly have all this and you can't store service . As as Capital expenditures is concerned you will not get benefit of ITC.
so my final word is that you can take ITC of your stored goods only you have before registration.

I am yet to take billing for the purchased goods, my question is for how long I can use the input-credit for tax settlement in future? Also, does govt. has any provision for input tax credit refund or it can be setlled for tax only?

If you are running restaurant ( not outdoor catering and lodging business) then you will not get ITC of any kind from 15/11/2017. as from 15/11/2017 GST on restaurant is 5% without Input Credit.

There is two concept one is booking of ITC and another one is utilization of ITC. When your ITC is reflected in Input tax credit ledger is called booking of ITC and when you set off your output tax liability against your ITC balance then is called utilization of ITC. Last date to book ITC of a financial year is generally 20th October or 31st Dec of Nxt FY , whichever is earlier.
As per your refund is concerned after booking ITC you can make application for refund u/s 54(3) and which will take 60 days for processed.

first of all expenses for renovation of building to be capitalised . you can't claim itc it is blocked under section 17(5)