need to redownload Acronis True Image OEM Activation (English)
You can download the installation file on the website of the manufacturer of the hardware you got your OEM license with, because OEM software is supported by OEM vendor: https://kb.acronis.com/content/2201
In any case please make sure that your Acronis True Image OEM version supports your new operating system.
if you have OEM software with activation key, this key should be accepted as an upgrade basis for Acronis True Image 2015 activation: first you enter your Acronis True Image 2015 upgrade serial number and then when requested a serial number of an OEM product.
If you face any difficulties with that, please contact our support team: http://www.acronis.com/support/contact-us.html
Instructions on how to download the installation file of an OEM version of Acronis True Image are generally provided with the hardware bundled with Acronis True Image. Please contact hardware vendor who supplied this OEM solution for more information.