You may upgrade at any time, provided that you are on the same platform. The upgrade process is quite simple and can be done by yourself through our control panel.
When your account is upgraded, you will not lose any data or account settings. Everything is retained as it is, but your account limits (disk space, traffic, number of databases, etc) will be increased.
Upgrading an account does NOT incur any extra upgrade fees. You will simply be charged for the new plan's fees.