I have translated your question to English as this is an International forum, please post any replies in English and it will be easier for me and other users to assist you.
Could you possibly elaborate your question a bit? For example, do you receive an error message when you try to purchase an app or does the download not start after you have placed the purchase? Also, have you checked whether you have a valid payment method added to your Google account or not? Open the Play store > Tap the three horizontal lines in the top left corner > Payment methods.
Please do elaborate as much as you can and I will do my best to assist you!