Since triangles \( NTE \) and \( KLA \) are similar, the ratios of the corresponding sides are equal. We can set up the ratio using the given side lengths:
\[ \frac{EN}{AK} = \frac{TE}{LA} \]
The values we have are:
- \( EN = 63 \)
- \( AK = 7 \)
- \( TE = 99 \)
Let \( LA \) be the unknown side length we need to find. Plugging in the known values, we have:
\[ \frac{63}{7} = \frac{99}{LA} \]
Now, we can simplify the left side:
\[ \frac{63}{7} = 9 \]
So the equation becomes:
\[ 9 = \frac{99}{LA} \]
Now, we can cross-multiply to solve for \( LA \):
\[ 9 \cdot LA = 99 \]
Dividing both sides by 9 gives:
\[ LA = \frac{99}{9} = 11 \]
Thus, the length of \( LA \) is \( \boxed{11} \).