If you use components that are licensed under GPLv3, then you are required to license the complete application the contains the GPL components under the GPL as well.
However, this is not all bad news, because the GPL only requires that you distribute the source code only to those persons that you distribute the binary to. If you never distribute the software to anyone, then you are also not required to give the sources away.
If you only provide remote access, then you are not distributing the software that runs on the server, so there are no distribution requirements for that. You have to be careful though if you also serve javascript parts that are executed on the client's machine, as that code is actually being distributed and might be affected by the GPL requirements.