How long can I use the free trial before purchasing the server edition?

How long can I use the free trial before purchasing the server edition?

There is no time limit. Evaluate as long as you require.

@lubos Do you mean evaluating with desktop version ?

Thanks,

I am running a school, I need to generate fees invoices and fee receipt for
parents.
Pls which module is suitable for that purposes?

You would use the Customer & Sale Invoices tabs to generate fees invoices
And Cash Account tab with Receive Money for fees receipt.

You can also do Receive Money via Sales Invoices