No doubt you can use same development token for your multiple applications which are accessing same account. If your applications will access different account then it needs to get different developer token.
For the reference, you can read http://goo.gl/zLBPF
Hope it will help you.
You can use the AdWords API across different applications with just one API token, just make sure though that you are caching the authentication response and re-using those tokens otherwise you'll hit the throttle limit. (Incidentally, logging in is possibly the slowest part of their API, so caching the response will speed up your application considerably)
Murali,
You need just one developer token, whether your application(s) access same account or different accounts (whether linked under the same MCC hierarchy or not). As a matter of fact, AdWords API Terms and Conditions explicitly prohibits you from getting more than one developer token.
If you use a developer token to make calls, you will be charged for API cost to the account holding the developer token. This is another reason why you should treat your developer token as a password and should reset it immediately if you expose it to the public by say, posting it publicly on a forum.
I also wish to point out that the official AdWords API forum is http://groups.google.com/group/adwords-api, you can ask your questions there and someone will answer your questions in a day or two.
Cheers, Anash
