You may have seen earlier this month that Google started testing a few new sale features on the Play Store. Select developers were able to set sale prices that showed up on the purchase button, and (finally) paid listings could be temporarily free. Now, that functionality is official. There's a support page with all the relevant details developers can check out.

There are a few important things to know before you go setting apps to free all willy-nilly. The new sale system is found under Pricing and Distribution in the dev console. When setting a sale, you can choose between one and eight days. Each app can only be placed on sale once every 30 days—i.e. there must be a 30-day gap between the end of on sale the start of the next. Developers have always been able to change their pricing before, but these tools include proper support in the way prices are displayed in the Play Store.

Paid apps and games can be made free, but this will impact your stats. Free downloads don't show up in the console as buyers and the app won't be listed on any top paid lists during the sale. From our testing, the game that was on sale for free a few weeks ago is still installable for those who picked it up at the time. That means temporarily free apps and games should remain accessible on your devices after the price goes back up.