This tutorial will be very basic and cover the main points on how to mod any Android app, but know that not all apps are the same and some can get pretty complex and hard to modify, the tutorial i will show is for beginners and later your skills will help you crack harder apps.
The things you will need to mod the applications
1. Android Phone (Root is not needed)
2. ApkEditorPro which allows dex2smali so make sure you download the one i have provided below. Here I will guide with APK Editor Pro abd Android Applications
This app is very simple to modify and is a prime example for beginners who want to modify an Android app, which has free and premium content, and you will need to purchase a sub-subscription. Premium fees for viewing premium content, but we will modify the app and make the app think we purchased premium.
Steps
1. Install APK Editor Pro and download the apk file from apkcombo.com, make sure you download the armeabi-v7a version since it is better and works on all devices and emulators.
2. Open up apk editor pro then hit “Select an Apk File”

3. Search for the apk file you just downloaded from apkcombo


4. Click on the APK file and select “Full Edit”

5. Press DEX> Smali you see at the bottom of the screen

6. The app do its work and output the smali files.When it’s done, the smali file will appear

7. Navigate to “Smali > com > blogilates > body” This is the main folder where all the good things that you can modify, usually the files are always inside the package name’s folder, for this app the package name is com.blogilates.body. The one you want to mod is model/User.smali

8. In other cases you will have many smali files and all will have such folders so you have to search yourself and try modifying things to see if they work, as i said not all apps will be this straightforward, some are complicated.
9. Click on User.smali
10. After clicking the User.smali file, search for ispremium keyword

11. Methods ending with ()Z are booleans so you can return either true or false to them, basically the app is verifying here whether the user is premium or not, and we will return true so it will think we are premium.
12. Remove everything from line 245 and 246, and write const v0, 0x1. Boolean values are stored as 1 for true and 0 for false.

13. Now save and build the apk file.Enjoy
14. Before

15. After

16. Other application have different membership types like Vip, Subscription, Pro, and other names so you will have to search accordingly, sometimes the app will have premium subscription but in smali it will have the name as Pro Subscription so you also have to look out for all that but that is something you will learn with time.