can i use my 4 Credits to purchase app ?

Hi RNCEBM,

Welcome to the Support Communities!

The article below should answer your question.

You can click on the link to see more details and screen shots.

I've highlighted the pertinent information for you below.

iTunes Store: How iTunes Store purchases are billed

http://support.apple.com/kb/HT5582

Order of iTunes billing methods

When making purchases, content credits are used first, followed by Gift Certificate, iTunes Card, or Allowance Account credits; your credit card or PayPal account is then charged for any remaining balance.

When you buy individual songs from the iTunes Store:

• Free song credits are redeemed first.
• If you have no free song credits, gift certificate, prepaid card, and allowance credits are used next.
• If your gift certificate, prepaid card, and/or allowance credit is less than the total cost of the purchase, your credit card is billed for the remaining balance.
• If you have no free song credits or gift certificates, prepaid cards, or allowance credits, your credit card is billed for the songs you buy.

When you buy an album on the iTunes Store:

• Gift certificate, prepaid card, and allowance credits are used first.
• If your gift certificate, prepaid card, or allowance credit is less than the total cost of the purchase, your credit card is billed for the remaining balance. Note: Free song credits cannot be used for album purchases.
• If you have no gift certificates, prepaid cards, or allowance credits, your credit card is billed for the albums you buy.

Cheers,

Judy