That's from the Play store, 99 cents isn't a bad deal for a damn good forum app..Tapatalk 4 - super launch sale!! $0.99. Was $4.99. Only one week. Upgrade Tapatalk 2 to Tapatalk 4 with HD tablet support for less than a dollar!
It looks like the week started yesterday, August 13th, if that's true the 20th would be the last day
Play link:
https://play.google.com/store/apps/details?id=com.quoord.tapatalkHD&hl=en