You can subscribe to Scheduled Premium for as little as $3.49 a month. This is the US price, non-US prices may differ. Find your country specific pricing in the AppStore or in Google Play.
With Premium, you get these awesome features:
The ability to Auto Send messages
You get 30 credits when you sign up, and after that 30 free credits per month. The credits are used for Auto Send messaging
Queue up unlimited prewritten reminder messages, instead of the 3 you get in the Free version
Import the birthdays of your contacts
Get your own archive with all your previously sent messages
How long does my subscription last?
All subscriptions are renewed monthly. If you have a monthly subscription, your subscription will renew each month on the day of your purchase. If you don't want your subscription to autorenew, be sure to cancel your subscription beforehand.