The integral given is \( \int e^{\sec x} \tan x \sec x \, dx \). We can use the substitution \( u = \sec x \), which gives \( du = \sec x \tan x \, dx \). The integral then simplifies to:
\[
\int e^{u} \, du = e^{u} + C
\]
Substituting back \( u = \sec x \), we get:
\[
e^{\sec x} + C
\]