email@example.com, if you use IM+ Pro, please make sure you have enabled the history saving fr your account in IM+.
To enable history please in IM+ go to "Settings" - "chat history" and tap "Enable history".
Then go to "Accounts", choose you account and switch on the "Chat history" switch.
Please note that IM+ for iPhone Lite doesn't support chat history saving.
SHAPE Services Support Team