You will be able to update RDPlus as long as your subscription to Support and Updates is active. 

You can renew your subscription to Support and Updates  at our on-line store here.
You have to select the proper edition and number of users, according to your current license.

You can order 1,2 or 3 years of subscription.

Updates are available from the Home tab of the admin tool by clicking on the version button as shown below :

Make sure no users are logged in before installing this update, you can check for remote users by launching a task manager and clicking on the users tab. 

Disabling your antivirus is also recommended. 

Make a scan exclusion rule on C:\wsession and C:\Program Files (x86)\RDPlus\UserDesktop\files and make sure your users have sufficient rights to read and execute all programs in these folders. 

A reboot will be required. 

You will find more detailed information about RDPlus updating process here :
https://rdplus.com.au/documents/updating-rdplus/