[anuaitt]

That can be done but it will affect user experience right ? Better will be if I stop further registrations for the app.

[hrjet]

An alternative: For non-premium users sync every 5 minutes.

For premium users sync every minute.

Use Indian payment gateways if possible, though Paypal works fine too.

[rattray]

This is exactly what you should do. Your users will understand -- that's why so many have supported you on the googlegroup. Charge $3/mo and you won't hear any complaints (and if you do, you can point to your googlegroup).

This is by far your easiest and clearest path to monetization, at least that I can see. And it seems you're long overdue for monetization.

[anuaitt]

Thanks hrjet, that is a great idea. But again I will have to struggle about the payment gateways. Thanks to HN guys for helping me out.

[cpeterso]

Can you adjust the sync rate depending on the time of day where your users live? There are probably certain times of the day when people update their tasks less frequently.