You can download past purchases on this device with just one Apple ID every 90 days. This device can be used with another Apple ID in 90 days.

Hello A.Somhpop

Your Apple ID can be associated with up to 10 devices. Once a new Apple ID is introduced it disables the other Apple ID for 90 days. The article below will give more information on the matter.

iTunes Store: Associating a device or computer to your Apple ID

http://support.apple.com/kb/ht4627

Thanks for using Apple Support Communities.

Regards,

-Norm G.

Correct. If you changed apple ID's and downloaded past purchases with a different ID then you block the original ID for 90 days.

There is nothing that can be done about it.

Its a security feature implemented by apple to prevent piracy.

You will have to wait 90 days to use your other Apple ID again, and if you download from that one, you will lock the other one for 90 days too.