Well, you can extend the applicability of a pattern to as many terms as you like, so ... there is no such thing as a finite pattern in the sense it is commonly construed.
On the other hand, regarding periodicity, there has to be some underlying frequency in tabulation as determining the nature of the series in question. Otherwise, there would be no pattern.
If there is something known and recognized as a pattern, it is only so because it is periodical. Even in chaos theory, in deriving a new Xp from a given Xp-1, we follow certain rules as overlapping our initial states.
On another tangent, a truly non-periodical pattern, it would appear, seems demanding of an infinite regress wherein irony is delivered to the persistent. Something like that cannot even conceptually exist in understanding, at least not to my current awareness nor concern.