Long term capital gain

I have allotment letter & BBA signed with the builder  in July’2009 with flat number properly marked & alloted (i.e.  I have got the right on the said property).  I sold the said flat in August'2013  i.e.  after 4 years from BBA date. My question is whether the Builder-buyer agreement is required to be registered in the office of registrar for claiming Long term capital gain.  In my case, BBA is signed on the stamp paper of Rs. 100/-, but it is not registered..  Can I clain LTCG  or else it is mandatory to rigister the BBA for claimimg LTCG.