best selling course :-)

Hi

I am going to make a course which is going to work on android and ios, but is going to be sold. But some problems;

1. How can I make a timer for that?

2. How can I sell it to every cellphone with kind of password or lock protection which lets just the phone uses that, not the others.

(Maybe the users get up to 3000)

3. This software is going to have 20 parts.

Which is better? 1. Make every parts and make them downloadable and when the user buys each part based on their own taste and make it run after payment?

2. Sell them part by part and user's taste and make a kind of pass?

Any way your mind goes; just tell me how?

Love you all.