First, make sure you are logged into the App Store with the same AppleID that you used to purchase the apps.
If that is not it, look in the App Store under Purchases. Are they there?
If not, go into your account in App Store and click the link to show hidden purchases.
If they are still not there, use the support link in the App Store.
If they do show up, copy all the apps to an external drive, then remove them from your Mac. Go to the App Store, Purchases, and install from there.
Thanks Barney. The apps were loaded when i bought the mac air from apple so the purchases do not show in apple store. they only show under applications on my mac. the store shows that an update is availble but will only tell me that i do not own the original application but i do on the mac. i have not tried removing apps to an external drive because i do not have an external drive. it is almost like the apple store just does not recognize software downloaded by apple. BUT when i search for the app it doesnt tell me to buy it, just update and then it wont let me update. does that help at all? i am at a loss except to call apple support???