Aviary is one of the more popular photo editors on Android. In the past there were various effect packs available for purchase, but in the latest update Aviary has added a premium upgrade. It's a little strange, though. For $1.99 you get access to all the effects, filters, stickers, and so on, but only for 30 days.
If you decide to buy premium (which is essentially a subscription, I guess), you'll need to sign in with a free Adobe ID. That's how Aviary syncs your supplies to other devices, but it includes 16 effects for free when you sign in. This update also adds a higher default save resolution and some bug fixes. If you go into the Aviary store, there are free tools and premium ones. It doesn't look like individual packs are listed in the app at all.
I'm not sure how many people are going to pay $1.99 for 30-day access to a bunch of filters and stickers. The early reviews are not particularly outraged, so maybe people are okay with this.