No. Gliffy Diagrams for Confluence/JIRA are completely separate products from Gliffy Online. All purchasing and licensing for the plugins are done through Atlassian and your my.atlassian.com account directly.
Gliffy Online can be purchased separately, but it cannot be connected in any way to a Confluence or JIRA instance.
There are also some limitations with transferring diagrams between products as noted here: http://support.gliffy.com/hc/en-us/articles/217895398-Can-I-import-gliffy-files-from-Gliffy-Online-into-Confluence-JIRA-
If you have further questions, please email firstname.lastname@example.org.