If you're using Skyfire with TPE on iOS then, no. The subscription does auto-renew. When it expires you will need to purchase another subscription. There is no need to cancel - you will not be automatically charged again. The same applies to free trials: they do not automatically convert into a paid subscription.
If you're using Skyfire for Android, then, yes. Please see this post for details on managing your subscription.
If you're using Photo Ephemeris Web, then, yes. Please see this post for more information on subscription options.