Concept: Easement by prescription is acquired by long, continuous and peaceful enjoyment of a right over another person's property.
Step 1: Understand prescription.
Prescription means acquisition of a right by long use. Such use must be open, peaceable and as of right.
\[
\text{Prescription} = \text{Long continuous use as of right}
\]
Step 2: Understand “as of right”.
“As of right” means the enjoyment must not be by force, secrecy or permission.
\[
\text{As of right} \neq \text{By permission}
\]
Step 3: Identify the condition which is not required.
If the enjoyment is by permission of the owner, then it is permissive use and cannot create easement by prescription.
Therefore, the correct answer is Enjoyment must be by permission of owner.