Usually, lucky patcher can't get around this kind of in-app purchase (subscription). It normally works for apps that have a one time purchase (but some apps have protection against this kind of patch)
However, once the app is patched, you don't need to run Lucky Patcher every time.
Finally, about its safety; I have been using it for a while, and never had any problems with it, so I reckon it is safe to use.
Yes, you can use emoji, but wouldn't it be better to use special characters instead? At least is 100% sure to be supported in all modern devices.