Easement by Prescription ka kya hai?

Main to aise questions pa raha hun jiske answer notes mein nahi hain, aur classes mein bhi Professor ne to sirf ek baar hamesha hi likhne ka formula diya hai, lekin uski pehchan samay nahi aayi. Main to bas yeh jaanta hoon ki easement by prescription ka basic concept toh hain ke koi person apna right establish karne ke liye long time tak uske upper aisa action rehta hai, lekin kya agar woh apna property change karta hai to kya uska easement intact rehta hai? Aur kya yeh saari court ke decision depend karta hai? Maine suna hai ki Shree Gopala Mills Ltd. vs. Smt.