For how many days can we keep our nail long ?

To keep long nails is against the Sunnah. Keeping long nails was considered as non civil practice and unsocial by sahabas. Hence it is not recommended since it may also prevent a pure complete wudhu cleanliness through accumulation dirts underneath nails. It is recommended as such to clean and shave every seven days. The limit to shave or remove hair under arm pit or private parts, cutting nails and trimming moustache is reported not more than 40 days. (Baihaqi) Beyond 40 days is makrouh tahreemi.