To access this option, from Settings, select the Licence tab:

The screen shows which package you are currently licensed for, the maximum user licenses i.e. the number of licences you have purchased; this is only relevant to multi-user accounts.

The screen also shows the number of licences that are allocated to users.

To upgrade a licence, click Upgrade License.

Depending on the package that you are currently subscribing to, the screen will then display the relevant upgrade information:

For example, a startup user will only have a single user account, when clicking on Upgrade Licence they will be presented with the option to choose the type of upgrade they require, increase the number of clients or increase the number of users:

Select an option and a new window will open showing you the costs and features for the different packages available:

Confirm your choice on the next screen and your package will be updated. The new invoice will need to be paid before you can upgrade again. This will take a few days to process.

Upgrades can be done at anytime and are not restricted to your invoice date. Should you upgrade midway through your invoice period, a credit for the portion of the subscription that you have not yet used will be automatically credited against your new invoice for the upgrade.